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1.  The association between drospirenone and hyperkalemia: a comparative-safety study 
Background
Drospirenone/ethinyl-estradiol is an oral contraceptive (OC) that possesses unique antimineralocorticoid activity. It is conjectured that drospirenone, taken alone or concomitantly with spironolactone, may be associated with an increased risk of hyperkalemia.
Methods
A retrospective cohort study was conducted evaluating women between 18-46 years of age in the Lifelink™ Health Plan Claims Database. The study was restricted to new users of OCs between 1997-2009. Cox proportional hazards models were used to estimate the time to first occurrence of hyperkalemia diagnosis. The main analysis compared OCs containing drospirenone with OCs containing levonorgestrel, a second generation OC not known to impact potassium homeostasis. Logistic regression evaluated concomitant prescribing of drospirenone and spironolactone
Results
The cohort included 1,148,183 women, averaging 28.8 years of age and 280 days of OC therapy. 2325 cases of hyperkalemia were identified. The adjusted hazard ratio (HR) for hyperkalemia with drospirenone compared to levonorgestrel was 1.10 (95%CI 0.95-1.26). There was an increased risk of hyperkalemia with norethindrone HR 1.15 (95%CI: 1.00-1.33) and norgestimate HR 1.27 (95%CI: 1.11-1.46). Other OCs were unassociated with hyperkalemia. The odds of receiving spironolactone while taking drospirenone were 2.66 (95%CI 2.53-2.80) times higher than the odds of receiving spironolactone and levonorgestrel. Only 6.5% of patients taking drospirenone and spironolactone had a serum potassium assay within 180 days of starting concomitant therapy.
Conclusions
A clinically significant signal for hyperkalemia with drospirenone was not demonstrated in the current study. Despite the bolded warning for hyperkalemia with joint drospirenone and spironolactone administration, physicians are actually using them together preferentially, and are not following the recommended potassium monitoring requirements in the package insert.
doi:10.1186/1472-6904-11-23
PMCID: PMC3265420  PMID: 22208934
2.  Hormonal contraception and risk of venous thromboembolism: national follow-up study 
Objective To assess the risk of venous thrombosis in current users of different types of hormonal contraception, focusing on regimen, oestrogen dose, type of progestogen, and route of administration.
Design National cohort study.
Setting Denmark, 1995-2005.
Participants Danish women aged 15-49 with no history of cardiovascular or malignant disease.
Main outcome measures Adjusted rate ratios for all first time deep venous thrombosis, portal thrombosis, thrombosis of caval vein, thrombosis of renal vein, unspecified deep vein thrombosis, and pulmonary embolism during the study period.
Results 10.4 million woman years were recorded, 3.3 million woman years in receipt of oral contraceptives. In total, 4213 venous thrombotic events were observed, 2045 in current users of oral contraceptives. The overall absolute risk of venous thrombosis per 10 000 woman years in non-users of oral contraceptives was 3.01 and in current users was 6.29. Compared with non-users of combined oral contraceptives the rate ratio of venous thrombembolism in current users decreased with duration of use (<1 year 4.17, 95% confidence interval 3.73 to 4.66, 1-4 years 2.98, 2.73 to 3.26, and >4 years 2.76, 2.53 to 3.02; P<0.001) and with decreasing dose of oestrogen. Compared with oral contraceptives containing levonorgestrel and with the same dose of oestrogen and length of use, the rate ratio for oral contraceptives with norethisterone was 0.98 (0.71 to 1.37), with norgestimate 1.19 (0.96 to 1.47), with desogestrel 1.82 (1.49 to 2.22), with gestodene 1.86 (1.59 to 2.18), with drospirenone 1.64 (1.27 to 2.10), and with cyproterone 1.88 (1.47 to 2.42). Compared with non-users of oral contraceptives, the rate ratio for venous thromboembolism in users of progestogen only oral contraceptives with levonorgestrel or norethisterone was 0.59 (0.33 to 1.03) or with 75 μg desogestrel was 1.12 (0.36 to 3.49), and for hormone releasing intrauterine devices was 0.90 (0.64 to 1.26).
Conclusion The risk of venous thrombosis in current users of combined oral contraceptives decreases with duration of use and decreasing oestrogen dose. For the same dose of oestrogen and the same length of use, oral contraceptives with desogestrel, gestodene, or drospirenone were associated with a significantly higher risk of venous thrombosis than oral contraceptives with levonorgestrel. Progestogen only pills and hormone releasing intrauterine devices were not associated with any increased risk of venous thrombosis.
doi:10.1136/bmj.b2890
PMCID: PMC2726928  PMID: 19679613
3.  Risk of venous thromboembolism from use of oral contraceptives containing different progestogens and oestrogen doses: Danish cohort study, 2001-9 
Objective To assess the risk of venous thromboembolism from use of combined oral contraceptives according to progestogen type and oestrogen dose.
Design National historical registry based cohort study.
Setting Four registries in Denmark.
Participants Non-pregnant Danish women aged 15-49 with no history of thrombotic disease and followed from January 2001 to December 2009.
Main outcome measures Relative and absolute risks of first time venous thromboembolism.
Results Within 8 010 290 women years of observation, 4307 first ever venous thromboembolic events were recorded and 4246 included, among which 2847 (67%) events were confirmed as certain. Compared with non-users of hormonal contraception, the relative risk of confirmed venous thromboembolism in users of oral contraceptives containing 30-40 µg ethinylestradiol with levonorgestrel was 2.9 (95% confidence interval 2.2 to 3.8), with desogestrel was 6.6 (5.6 to 7.8), with gestodene was 6.2 (5.6 to 7.0), and with drospirenone was 6.4 (5.4 to 7.5). With users of oral contraceptives with levonorgestrel as reference and after adjusting for length of use, the rate ratio of confirmed venous thromboembolism for users of oral contraceptives with desogestrel was 2.2 (1.7 to 3.0), with gestodene was 2.1 (1.6 to 2.8), and with drospirenone was 2.1 (1.6 to 2.8). The risk of confirmed venous thromboembolism was not increased with use of progestogen only pills or hormone releasing intrauterine devices. If oral contraceptives with desogestrel, gestodene, or drospirenone are anticipated to increase the risk of venous thromboembolism sixfold and those with levonorgestrel threefold, and the absolute risk of venous thromboembolism in current users of the former group is on average 10 per 10 000 women years, then 2000 women would need to shift from using oral contraceptives with desogestrel, gestodene, or drospirenone to those with levonorgestrel to prevent one event of venous thromboembolism in one year.
Conclusion After adjustment for length of use, users of oral contraceptives with desogestrel, gestodene, or drospirenone were at least at twice the risk of venous thromboembolism compared with users of oral contraceptives with levonorgestrel.
doi:10.1136/bmj.d6423
PMCID: PMC3202015  PMID: 22027398
4.  Continuation rates of oral hormonal contraceptives in a cohort of first-time users: a population-based registry study, Sweden 2005–2010 
BMJ Open  2013;3(10):e003401.
Objective
To investigate if continuation rates in first-time users of oral hormonal contraceptives differed between different formulations and to measure if the rates were related to the prescribing categories, that is, physicians and midwives.
Design
A longitudinal national population-based registry study.
Setting
The Swedish prescribed drug register.
Participants
All women born between 1977 and 1994 defined as first-time users of hormonal contraceptives from 2007 to 2009 (n=226 211).
Main outcome measures
A tendency to switch the type of hormonal contraceptive within 6 months use and repeated dispensation identical to the first were estimated as percentages and relative risks (RRs). Physicians’ and midwives’ prescription patterns concerning the women's continuation rates of oral hormonal contraceptive type.
Results
In Sweden, there were 782 375 women born between 1977 and 1994 at the time of the study. Of these, 226 211 women were identified as first-time users of hormonal contraceptives. Ethinylestradiol+levonorgestrel, desogestrel-only and ethinylestradiol+drospirenone were the hormonal contraceptives most commonly dispensed to first-time users at rates of 43.3%, 24.4% and 11.1%, respectively. The overall rate of switching contraceptive types in the first 6 months was 11.3%, which was highest for desogestrel-only (14.3%) and lowest for ethinylestradiol+drospirenone (6.6%). The switching rate for all three products was highest in the 16-year to 19-year age group. Having a repeated dispensation identical to the initial dispensation was highest for users of ethinylestradiol either combined with levonorgestrel or drospirenone, 81.4% and 81.2%, respectively, whereas this rate for the initial desogestrel-only users was 71.5%. The RR of switching of contraceptive type within the first 6 months was 1.35 (95% CI 1.32 to 1.39) for desogestrel-only and 0.63 (0.59 to 0.66) for ethinylestradiol+drospirenone compared with ethinylestradiol+levonorgestrel as the reference category. There were no differences in the women's continuation rates depending on the prescriber categories.
Conclusions
Desogestrel-only users conferred the highest switcher rate to another hormonal contraceptive within a 6-month period. Users of ethinylestradiol+levonorgestrel were more prone to switch to another product within 6 months than women using ethinylestradiol+drospirenone. These findings may be of clinical importance when tailoring hormonal contraceptives on an individual basis.
doi:10.1136/bmjopen-2013-003401
PMCID: PMC3808784  PMID: 24141970
Public Health
5.  Risk of non-fatal venous thromboembolism in women using oral contraceptives containing drospirenone compared with women using oral contraceptives containing levonorgestrel: case-control study using United States claims data 
Objective To compare the risk of non-fatal venous thromboembolism in women receiving oral contraceptives containing drospirenone with that in women receiving oral contraceptives containing levonorgestrel.
Design Nested case-control and cohort study.
Setting The study was based on information from PharMetrics, a United States based company that collects information on claims paid by managed care plans.
Participants The study encompassed all women aged 15 to 44 years who received an oral contraceptive containing either drospirenone or levonorgestrel after 1 January 2002. Cases were women with current use of a study oral contraceptive and a diagnosis of venous thromboembolism in the absence of identifiable clinical risk factors (idiopathic venous thromboembolism). Up to four controls were matched to each case by age and calendar time.
Main outcome measures Odds ratios comparing the risk of non-fatal venous thromboembolism in users of the two contraceptives; incidence rates and rate ratios of non-fatal venous thromboembolism for users of each of the study contraceptives.
Results 186 newly diagnosed, idiopathic cases of venous thromboembolism were identified in the study population and matched with 681 controls. In the case-control analysis, the conditional odds ratio for venous thromboembolism comparing use of oral contraceptives containing drospirenone with use of those containing levonorgestrel was 2.3 (95% confidence interval 1.6 to 3.2). The incidence rates for venous thromboembolism in the study population were 30.8 (95% confidence interval 25.6 to 36.8) per 100 000 woman years among users of oral contraceptives containing drospirenone and 12.5 (9.61 to 15.9) per 100 000 woman years among users of oral contraceptives containing levonorgestrel. The age adjusted incidence rate ratio for venous thromboembolism for current use of oral contraceptives containing drospirenone compared with those containing levonorgestrel was 2.8 (2.1 to 3.8).
Conclusions The risk of non-fatal venous thromboembolism among users of oral contraceptives containing drospirenone seems to be around twice that of users of oral contraceptives containing levonorgestrel, after the effects of potential confounders and prescribing biases have been taken into account.
doi:10.1136/bmj.d2151
PMCID: PMC3081040  PMID: 21511805
6.  Different combined oral contraceptives and the risk of venous thrombosis: systematic review and network meta-analysis 
Objective To provide a comprehensive overview of the risk of venous thrombosis in women using different combined oral contraceptives.
Design Systematic review and network meta-analysis.
Data sources PubMed, Embase, Web of Science, Cochrane, Cumulative Index to Nursing and Allied Health Literature, Academic Search Premier, and ScienceDirect up to 22 April 2013.
Review methods Observational studies that assessed the effect of combined oral contraceptives on venous thrombosis in healthy women. The primary outcome of interest was a fatal or non-fatal first event of venous thrombosis with the main focus on deep venous thrombosis or pulmonary embolism. Publications with at least 10 events in total were eligible. The network meta-analysis was performed using an extension of frequentist random effects models for mixed multiple treatment comparisons. Unadjusted relative risks with 95% confidence intervals were reported. The requirement for crude numbers did not allow adjustment for potential confounding variables.
Results 3110 publications were retrieved through a search strategy; 25 publications reporting on 26 studies were included. Incidence of venous thrombosis in non-users from two included cohorts was 1.9 and 3.7 per 10 000 woman years, in line with previously reported incidences of 1-6 per 10 000 woman years. Use of combined oral contraceptives increased the risk of venous thrombosis compared with non-use (relative risk 3.5, 95% confidence interval 2.9 to 4.3). The relative risk of venous thrombosis for combined oral contraceptives with 30-35 µg ethinylestradiol and gestodene, desogestrel, cyproterone acetate, or drospirenone were similar and about 50-80% higher than for combined oral contraceptives with levonorgestrel. A dose related effect of ethinylestradiol was observed for gestodene, desogestrel, and levonorgestrel, with higher doses being associated with higher thrombosis risk.
Conclusion All combined oral contraceptives investigated in this analysis were associated with an increased risk of venous thrombosis. The effect size depended both on the progestogen used and the dose of ethinylestradiol.
doi:10.1136/bmj.f5298
PMCID: PMC3771677  PMID: 24030561
7.  Risk of venous thromboembolism in users of oral contraceptives containing drospirenone or levonorgestrel: nested case-control study based on UK General Practice Research Database 
Objective To examine the risk of non-fatal idiopathic venous thromboembolism in current users of a combined oral contraceptive containing drospirenone, relative to current users of preparations containing levonorgestrel.
Design Nested case-control study.
Setting UK General Practice Research Database.
Participants Women aged 15-44 years without major risk factors for venous thromboembolism who started a new episode of use of an oral contraceptive containing 30 µg oestrogen in combination with either drospirenone or levonorgestrel between May 2002 and September 2009. Cases were women with a first diagnosis of venous thromboembolism; up to four controls, matched by age, duration of recorded information, and general practice, were randomly selected for each case.
Main outcome measures Odds ratios and 95% confidence intervals estimated with conditional logistic regression; age adjusted incidence rate ratio estimated with Poisson regression.
Results 61 cases of idiopathic venous thromboembolism and 215 matched controls were identified. In the case-control analysis, current use of the drospirenone contraceptive was associated with a threefold higher risk of non-fatal idiopathic venous thromboembolism compared with levonorgestrel use; the odds ratio adjusted for body mass index was 3.3 (95% confidence interval 1.4 to 7.6). Subanalyses suggested that referral, diagnostic, first time user, duration of use, and switching biases were unlikely explanations for this finding. The crude incidence rate was 23.0 (95% confidence interval 13.4 to 36.9) per 100 000 woman years in current users of drospirenone and 9.1 (6.6 to 12.2) per 100 000 woman years in current users of levonorgestrel oral contraceptives. The age adjusted incidence rate ratio was 2.7 (1.5 to 4.7).
Conclusions These findings contribute to emerging evidence that the combined oral contraceptive containing drospirenone carries a higher risk of venous thromboembolism than do formulations containing levonorgestrel.
doi:10.1136/bmj.d2139
PMCID: PMC3081041  PMID: 21511804
8.  Injectable and Oral Contraceptive Use and Cancers of the Breast, Cervix, Ovary, and Endometrium in Black South African Women: Case–Control Study 
PLoS Medicine  2012;9(3):e1001182.
A case-control study conducted in South Africa provides new estimates of the risk of specific cancers of the female reproductive system associated with use of injectable and oral contraceptives.
Background
Oral contraceptives are known to influence the risk of cancers of the female reproductive system. Evidence regarding the relationship between injectable contraceptives and these cancers is limited, especially in black South Africans, among whom injectable contraceptives are used more commonly than oral contraceptives.
Methods and Findings
We analysed data from a South African hospital-based case–control study of black females aged 18–79 y, comparing self-reported contraceptive use in patients with breast (n = 1,664), cervical (n = 2,182), ovarian (n = 182), and endometrial (n = 182) cancer, with self-reported contraceptive use in 1,492 control patients diagnosed with cancers with no known relationship to hormonal contraceptive use. We adjusted for potential confounding factors, including age, calendar year of diagnosis, education, smoking, alcohol, parity/age at first birth, and number of sexual partners. Among controls, 26% had used injectable and 20% had used oral contraceptives. For current and more recent users versus never users of oral or injectable contraceptives, the odds ratios (ORs) for breast cancer were significantly increased in users of oral and/or injectable contraceptives (OR 1.66, 95% CI 1.28–2.16, p<0.001) and separately among those exclusively using oral (1.57, 1.03–2.40, p = 0.04) and exclusively using injectable (OR 1.83, 1.31–2.55, p<0.001) contraceptives; corresponding ORs for cervical cancer were 1.38 (1.08–1.77, p = 0.01), 1.01 (0.66–1.56, p = 0.96), and 1.58 (1.16–2.15, p = 0.004). There was no significant increase in breast or cervical cancer risk among women ceasing hormonal contraceptive use ≥10 y previously (p = 0.3 and p = 0.9, respectively). For durations of use ≥5 y versus never use, the ORs of ovarian cancer were 0.60 (0.36–0.99, p = 0.04) for oral and/or injectable contraceptive use and 0.07 (0.01–0.49, p = 0.008) for injectable use exclusively; corresponding ORs for endometrial cancer were 0.44 (0.22–0.86, p = 0.02) and 0.36 (0.11–1.26, p = 0.1).
Conclusions
In this study, use of oral and of injectable hormonal contraceptives was associated with a transiently increased risk of breast and cervical cancer and, for long durations of use, with a reduced risk of ovarian and endometrial cancer. The observed effects of injectable and of oral contraceptives on cancer risk in this study did not appear to differ substantially.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
Hormonal contraceptives are among the most commonly used medications. Globally, more than 210 million women currently use either hormonal contraceptive pills or injectable contraceptives. Contraceptive pills usually contain manmade versions of the female sex hormones estrogen and progesterone (the combined oral contraceptive, or “pill”); most injectable hormonal contraceptives contain only manmade progesterone preparations. Hormonal contraceptives, which prevent pregnancy by disrupting the cyclical changes in estrogen and progesterone levels that prepare the body for pregnancy, have revolutionized birth control since they first became available in the early 1960s. However, it is now known that taking the pill also influences women's risk of developing cancers of the female reproductive system. Current and recent users have an increased risk of developing breast and cervical cancer (the cervix is the structure that connects the womb to the vagina) compared to never users, although this increased risk quickly disappears when women stop taking the pill. By contrast, women who have used the pill have a reduced risk of developing ovarian cancer and cancer of the womb (endometrial cancer) compared to never users that increases with the duration of pill use and persists for many years after use ceases. These effects on reproductive system cancers are thought to occur because these cancers depend on naturally occurring sex hormones for their development and growth.
Why Was This Study Done?
Although the evidence that the pill influences the risk of developing cancers of the female reproductive system is extensive, much less is known about how injectable hormonal contraceptives affect cancer risk. In this hospital-based case–control study (a study that compares the characteristics of people with and without a specific condition), the researchers investigate the relationship between the use of oral and injectable hormonal contraceptives and cancers of the breast, cervix, ovary, and endometrium among black South African women. Injectable contraceptives have been used for longer in South Africa than elsewhere and are used more commonly than oral contraceptives among black South African women.
What Did the Researchers Do and Find?
As part of the Johannesburg Cancer Case Control Study, which recruits black patients attending Johannesburg public referral hospitals for cancer treatment, the researchers compared hormonal contraceptive use in women with breast, cervical, ovarian, or endometrial cancer with contraceptive use in women diagnosed with other cancers such as lung, colon, and rectal cancers, which are not known to be influenced by hormonal contraceptives. Among the controls, a quarter had used injectable contraceptives and a fifth had used oral contraceptives. After adjusting for other factors that might influence cancer risk such as age, smoking, and number of sexual partners, the odds ratio (OR) of breast cancer among current and recent users of oral and/or injectable contraceptives compared to never users was 1.66. That is, the risk of developing breast cancer among current and recent users of hormonal contraceptives was 1.66 times that among never users. For women using oral contraceptives exclusively or injectable contraceptives exclusively, the ORs of breast cancer were 1.57 and 1.83, respectively. There were also increases in cervical cancer risk among current and recent users of hormonal contraceptives compared to never users, but no significant increase in breast or cervical cancer risk among women who had ceased hormonal contraceptive use more than ten years previously. Finally, the use of hormonal contraceptives for more than five years reduced the risk of both ovarian and endometrial cancer.
What Do These Findings Mean?
These findings indicate that, among black women in South Africa, the use of oral or injectable hormonal contraceptives is associated with a transiently increased risk of breast and cervical cancer, and that extended use of these contraceptives is associated with a reduced risk of ovarian and endometrial cancer. Moreover, they suggest that the effects of oral versus injectable contraceptives on cancer risk do not differ substantially, although for endometrial and ovarian cancer the small number of cases exposed to injectable contraceptives limits the accuracy of the risk estimates. Other limitations of this study include the possibility that the findings may be affected by uncontrolled confounding. That is, women who used hormonal contraceptives may have shared other unidentified characteristics that affected their cancer risk. Nevertheless, these findings provide new information about the effects of oral and injectable hormonal contraceptives on cancer risk that should help women make informed decisions about their choice of contraceptive method.
Additional Information
Please access these web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001182.
The US National Cancer Institute provides information on breast cancer (including personal stories from breast cancer survivors), cervical cancer, ovarian cancer, and endometrial cancer for patients and health professionals, and a fact sheet on oral contraceptives and cancer risk (in English and Spanish)
Cancer Research UK also provides information on breast cancer, cervical cancer, ovarian cancer, and endometrial cancer and information about the birth control pill and cancer risk
Eyes on the Prize, an online support group for women who have had cancers of the female reproductive system, has personal stories; further personal stories about breast, cervical, and ovarian cancer are provided by the charity Healthtalkonline
doi:10.1371/journal.pmed.1001182
PMCID: PMC3295825  PMID: 22412354
9.  Hormonal Contraception and the Risk of HIV Acquisition: An Individual Participant Data Meta-analysis 
PLoS Medicine  2015;12(1):e1001778.
In a meta-analysis of individual participant data, Charles Morrison and colleagues explore the association between hormonal contraception use and risk of HIV infection in sub-Saharan Africa.
Background
Observational studies of a putative association between hormonal contraception (HC) and HIV acquisition have produced conflicting results. We conducted an individual participant data (IPD) meta-analysis of studies from sub-Saharan Africa to compare the incidence of HIV infection in women using combined oral contraceptives (COCs) or the injectable progestins depot-medroxyprogesterone acetate (DMPA) or norethisterone enanthate (NET-EN) with women not using HC.
Methods and Findings
Eligible studies measured HC exposure and incident HIV infection prospectively using standardized measures, enrolled women aged 15–49 y, recorded ≥15 incident HIV infections, and measured prespecified covariates. Our primary analysis estimated the adjusted hazard ratio (aHR) using two-stage random effects meta-analysis, controlling for region, marital status, age, number of sex partners, and condom use. We included 18 studies, including 37,124 women (43,613 woman-years) and 1,830 incident HIV infections. Relative to no HC use, the aHR for HIV acquisition was 1.50 (95% CI 1.24–1.83) for DMPA use, 1.24 (95% CI 0.84–1.82) for NET-EN use, and 1.03 (95% CI 0.88–1.20) for COC use. Between-study heterogeneity was mild (I2 < 50%). DMPA use was associated with increased HIV acquisition compared with COC use (aHR 1.43, 95% CI 1.23–1.67) and NET-EN use (aHR 1.32, 95% CI 1.08–1.61). Effect estimates were attenuated for studies at lower risk of methodological bias (compared with no HC use, aHR for DMPA use 1.22, 95% CI 0.99–1.50; for NET-EN use 0.67, 95% CI 0.47–0.96; and for COC use 0.91, 95% CI 0.73–1.41) compared to those at higher risk of bias (pinteraction = 0.003). Neither age nor herpes simplex virus type 2 infection status modified the HC–HIV relationship.
Conclusions
This IPD meta-analysis found no evidence that COC or NET-EN use increases women’s risk of HIV but adds to the evidence that DMPA may increase HIV risk, underscoring the need for additional safe and effective contraceptive options for women at high HIV risk. A randomized controlled trial would provide more definitive evidence about the effects of hormonal contraception, particularly DMPA, on HIV risk.
Editors’ Summary
Background
AIDS has killed about 36 million people since the first recorded case of the disease in 1981. About 35 million people (including 25 million living in sub-Saharan Africa) are currently infected with HIV, the virus that causes AIDS, and every year, another 2.3 million people become newly infected with HIV. At the beginning of the epidemic, more men than women were infected with HIV. Now, about half of all adults infected with HIV are women. In 2013, almost 60% of all new HIV infections among young people aged 15–24 years occurred among women, and it is estimated that, worldwide, 50 young women are newly infected with HIV every hour. Most women become infected with HIV through unprotected intercourse with an infected male partner—biologically, women are twice as likely to become infected through unprotected intercourse as men. A woman’s risk of becoming infected with HIV can be reduced by abstaining from sex, by having one or a few partners, and by always using condoms.
Why Was This Study Done?
Women and societies both benefit from effective contraception. When contraception is available, women can avoid unintended pregnancies, fewer women and babies die during pregnancy and childbirth, and maternal and infant health improves. However, some (but not all) observational studies (investigations that measure associations between the characteristics of participants and their subsequent development of specific diseases) have reported an association between hormonal contraceptive use and an increased risk of HIV acquisition by women. So, does hormonal contraception increase the risk of HIV acquisition among women or not? Here, to investigate this question, the researchers undertake an individual participant data meta-analysis of studies conducted in sub-Saharan Africa (a region where both HIV infection and unintended pregnancies are common) to compare the incidence of HIV infection (the number of new cases in a population during a given time period) among women using and not using hormonal contraception. Meta-analysis is a statistical method that combines the results of several studies; an individual participant data meta-analysis combines the data recorded for each individual involved in the studies rather than the aggregated results from each study.
What Did the Researchers Do and Find?
The researchers included 18 studies that measured hormonal contraceptive use and incident HIV infection among women aged 15–49 years living in sub-Saharan Africa in their meta-analysis. More than 37,000 women took part in these studies, and 1,830 became newly infected with HIV. Half of the women were not using hormonal contraception, a quarter were using depot-medroxyprogesterone acetate (DMPA; an injectable hormonal contraceptive), and the remainder were using combined oral contraceptives (COCs) or norethisterone enanthate (NET-EN, another injectable contraceptive). After adjustment for other factors likely to influence HIV acquisition (for example, condom use), women using DMPA had a 1.5-fold increased risk of HIV acquisition compared to women not using hormonal contraception. There was a slightly increased risk of HIV acquisition among women using NET-EN compared to women not using hormonal contraception, but this increase was not statistically significant (it may have happened by chance alone). There was no increased risk of HIV acquisition associated with COC use. DMPA use was associated with a 1.43-fold and 1.32-fold increased risk of HIV acquisition compared with COC and NET-EN use, respectively. Finally, neither age nor herpes simplex virus 2 infection status modified the effect of hormonal contraceptive use on HIV acquisition.
What Do These Findings Mean?
The findings of this individual patient data meta-analysis provide no evidence that COC or NET-EN use increases a woman’s risk of acquiring HIV, but add to the evidence suggesting that DMPA use increases the risk of HIV acquisition. These findings are likely to be more accurate than those of previous meta-analyses that used aggregated data but are likely to be limited by the quality, design, and representativeness of the studies included in the analysis. These findings nevertheless highlight the need to develop additional safe and effective contraceptive options for women at risk of HIV, particularly those living in sub-Saharan Africa, where although contraceptive use is generally low, DMPA is the most widely used hormonal contraceptive. In addition, these findings highlight the need to initiate randomized controlled trials to provide more definitive evidence of the effects of hormonal contraception, particularly DMPA, on HIV risk.
Additional Information.
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001778.
Information is available from the US National Institute of Allergy and Infectious Diseases on HIV infection and AIDS
NAM/aidsmap provides basic information about HIV/AIDS, and summaries of recent research findings on HIV care and treatment, including personal stories about living with HIV/AIDS and a news report on this meta-analysis
Information is available from Avert, an international AIDS charity, on many aspects of HIV/AIDS, including detailed information on women, HIV, and AIDS, and on HIV and AIDS in South Africa (in English and Spanish); personal stories of women living with HIV are available
The World Health Organization provides information on all aspects of HIV/AIDS (in several languages); information about a 2012 WHO technical consultation about hormonal contraception and HIV
The 2013 UNAIDS World AIDS Day report provides up-to-date information about the AIDS epidemic and efforts to halt it; UNAIDS also provides information about HIV and hormonal contraception
doi:10.1371/journal.pmed.1001778
PMCID: PMC4303292  PMID: 25612136
10.  Safety, efficacy and patient satisfaction with continuous daily administration of levonorgestrel/ethinylestradiol oral contraceptives 
The progestational steroid norgestrel was synthesized and tested between 1960 and 1965 through an international cooperation between Wyeth, USA and Schering, Berlin. It is a mixture of two “enantiomers,” with only one form (designated as levonorgestrel) biologically active. When taken orally, it is rapidly absorbed, not subjected to a “first-pass” effect and is approximately 90% bioavailable, with a circulating half-life around 15 hours. Its contraceptive action is exerted at the central (hypothalamic) and peripheral (cervical mucus and endometrium) levels. Levonorgestrel (LNG), alone or in combination with ethinyl estradiol (EE), is the most widely employed contraceptive progestin: it is used in combined oral contraceptives, progestogen-only pills, long-acting contraceptive implants, intrauterine contraceptive systems and in emergency contraception. It is also the steroid of choice for new oral contraceptive regimens aimed at reducing the frequency of bleeding episodes. This novel approach, already tried more than 30 years ago, gained interest around the year 2000 when surveys of women’s attitudes toward monthly menstrual bleeding started to show a major change: more and more women declared that they would welcome a hormonal contraceptive method that reduced bleeding episodes to 4, 2 or even 1 per year. At this point, while the debate on the significance and “usefulness” of menstruation went on, attention focused on new regimens. The first new modality consisted of changing the 7-day medication-free interval, either shortening it to fewer than 7 days, or by the administration of low-dose estrogens during the interval between packages. Then, continuous administration regimens started to be investigated. This, however, did not happen suddenly, since, in specific situations, doctors had for years empirically utilized various continuous administration regimens. The first extended-cycle oral contraceptive regimen introduced in clinical practice is an 84-day regimen that results in bleeding only 4 times a year. A commercial product specifically packed for continuous use is now available in Europe and contains 30 μg EE and 150 μg LNG. In a variation of this regimen, after administration of the same combination for 84 days, women are given 7 pills containing 10 μg EE. A 6-monthly regimen has also been tested in a small study using EE 20 μg plus LNG 100 μg taken with and without a hormone-free interval. Women in the continuous group reported significantly fewer bleeding days requiring protection and were more likely to have amenorrhea; in addition they also reported significantly fewer days of bloating and menstrual pain. A yearly regimen is now being developed. Each pill of this novel formulation contains EE 20 μg and LNG 90 μg to be taken continuously for 364 days (13 cycles) per year. A phase III trial has now evaluated safety, efficacy and menses inhibition. At the end of the 1-year trial amenorrhea was present in 58.7% of the women and a complete absence of bleeding in 79.0%. Overall, the number of bleeding and spotting days per pill pack declined with time and adverse events and discontinuations were comparable to those reported for cyclic oral contraceptive regimens.
PMCID: PMC2778424  PMID: 19936155
levonorgestrel; oral contraceptive; continuous administration; menstruation; amenorrhea
11.  The venous thrombotic risk of oral contraceptives, effects of oestrogen dose and progestogen type: results of the MEGA case-control study 
Objective To assess the thrombotic risk associated with oral contraceptive use with a focus on dose of oestrogen and type of progestogen of oral contraceptives available in the Netherlands.
Design Population based case-control study.
Setting Six participating anticoagulation clinics in the Netherlands (Amersfoort, Amsterdam, The Hague, Leiden, Rotterdam, and Utrecht).
Participants Premenopausal women <50 years old who were not pregnant, not within four weeks postpartum, and not using a hormone excreting intrauterine device or depot contraceptive. Analysis included 1524 patients and 1760 controls.
Main outcome measures First objectively diagnosed episodes of deep venous thrombosis of the leg or pulmonary embolism. Odds ratios calculated by cross-tabulation with a 95% confidence interval according to Woolf’s method; adjusted odds ratios estimated by unconditional logistic regression, standard errors derived from the model.
Results Currently available oral contraceptives increased the risk of venous thrombosis fivefold compared with non-use (odds ratio 5.0, 95% CI 4.2 to 5.8). The risk clearly differed by type of progestogen and dose of oestrogen. The use of oral contraceptives containing levonorgestrel was associated with an almost fourfold increased risk of venous thrombosis (odds ratio 3.6, 2.9 to 4.6) relative to non-users, whereas the risk of venous thrombosis compared with non-use was increased 5.6-fold for gestodene (5.6, 3.7 to 8.4), 7.3-fold for desogestrel (7.3, 5.3 to 10.0), 6.8-fold for cyproterone acetate (6.8, 4.7 to 10.0), and 6.3-fold for drospirenone (6.3, 2.9 to 13.7). The risk of venous thrombosis was positively associated with oestrogen dose. We confirmed a high risk of venous thrombosis during the first months of oral contraceptive use irrespective of the type of oral contraceptives.
Conclusions Currently available oral contraceptives still have a major impact on thrombosis occurrence and many women do not use the safest brands with regard to risk of venous thrombosis.
doi:10.1136/bmj.b2921
PMCID: PMC2726929  PMID: 19679614
12.  Risk of venous thromboembolism among users of third generation oral contraceptives compared with users of oral contraceptives with levonorgestrel before and after 1995: cohort and case-control analysis 
BMJ : British Medical Journal  2000;321(7270):1190-1195.
Objective
To compare the risk of idiopathic venous thromboembolism among women taking third generation oral contraceptives (with gestodene or desogestrel) with that among women taking oral contraceptives with levonorgestrel.
Design
Cohort and case-control analyses derived from the General Practice Research Database.
Setting
UK general practices, January 1993 to December 1999.
Participants
Women aged 15-39 taking third generation oral contraceptives or oral contraceptives with levonorgestrel.
Main outcome measures
Relative incidence (cohort study) and odds ratios (case-control study) as measures of the relative risk of venous thromboembolism.
Results
The adjusted estimates of relative risk for venous thromboembolism associated with third generation oral contraceptives compared with oral contraceptives with levonorgestrel was 1.9 (95% confidence interval 1.3 to 2.8) in the cohort analysis and 2.3 (1.3 to 3.9) in the case-control study. The estimates for the two types of oral contraceptives were similar before and after the warning issued by the Committee on Safety of Medicines in October 1995. A shift away from the use of third generation oral contraceptives after the scare was more pronounced among younger women (who have a lower risk of venous thromboembolism) than among older women. Fewer cases of venous thromboembolism occurred in 1996 and later than would have been expected if the use of oral contraceptives had remained unchanged.
Conclusions
These findings are consistent with previously reported studies, which found that compared with oral contraceptives with levonorgestrel, third generation oral contraceptives are associated with around twice the risk of venous thromboembolism.
PMCID: PMC27524  PMID: 11073511
13.  Higher risk of venous thrombosis associated with drospirenone-containing oral contraceptives: a population-based cohort study 
Background:
Combined oral contraceptives are a common method of contraception, but they carry a risk of venous and arterial thrombosis. We assessed whether use of drospirenone was associated with an increase in thrombotic risk relative to third-generation combined oral contraceptives.
Methods:
Using computerized records of the largest health care provider in Israel, we identified all women aged 12 to 50 years for whom combined oral contraceptives had been dispensed between Jan. 1, 2002, and Dec. 31, 2008. We followed the cohort until 2009. We used Poisson regression models to estimate the crude and adjusted rate ratios for risk factors for venous thrombotic events (specifically deep vein thrombosis and pulmonary embolism) and arterial thromboic events (specifically transient ischemic attack and cerebrovascular accident). We performed multivariable analyses to compare types of contraceptives, with adjustment for the various risk factors.
Results:
We identified a total of 1017 (0.24%) venous and arterial thrombotic events among 431 223 use episodes during 819 749 woman-years of follow-up (6.33 venous events and 6.10 arterial events per 10 000 woman-years). In a multivariable model, use of drospirenone carried an increased risk of venous thrombotic events, relative to both third-generation combined oral contraceptives (rate ratio [RR] 1.43, 95% confidence interval [CI] 1.15–1.78) and second-generation combined oral contraceptives (RR 1.65, 95% CI 1.02–2.65). There was no increase in the risk of arterial thrombosis with drospirenone.
Interpretation:
Use of drospirenone-containing oral contraceptives was associated with an increased risk of deep vein thrombosis and pulmonary embolism, but not transient ischemic attack or cerebrovascular attack, relative to second- and third-generation combined oral contraceptives.
doi:10.1503/cmaj.110463
PMCID: PMC3255137  PMID: 22065352
14.  Third generation oral contraceptives and risk of venous thrombosis: meta-analysis 
BMJ : British Medical Journal  2001;323(7305):131.
Objective
To evaluate quantitatively articles that compared effects of second and third generation oral contraceptives on risk of venous thrombosis.
Design
Meta-analysis.
Studies
Cohort and case-control studies assessing risk of venous thromboembolism among women using oral contraceptives before October 1995.
Main outcome measures
Pooled adjusted odds ratios calculated by a general variance based random effects method. When possible, two by two tables were extracted and combined by the Mantel-Haenszel method.
Results
The overall adjusted odds ratio for third versus second generation oral contraceptives was 1.7 (95% confidence interval 1.4 to 2.0; seven studies). Similar risks were found when oral contraceptives containing desogestrel or gestodene were compared with those containing levonorgestrel. Among first time users, the odds ratio for third versus second generation preparations was 3.1 (2.0 to 4.6; four studies). The odds ratio was 2.5 (1.6 to 4.1; five studies) for short term users compared with 2.0 (1.4 to 2.7; five studies) for longer term users. The odds ratio was 1.3 (1.0 to 1.7) in studies funded by the pharmaceutical industry and 2.3 (1.7 to 3.2) in other studies. Differences in age and certainty of diagnosis of venous thrombosis did not affect the results.
Conclusions
This meta-analysis supports the view that third generation oral contraceptives are associated with an increased risk of venous thrombosis compared with second generation oral contraceptives. The increase cannot be explained by several potential biases.
What is already known on this topicThird generation oral contraceptives have been reported to increase the risk of venous thrombosis compared with second generation oral contraceptivesThe findings have been vigorously debated, with suggestions that the results can be explained by confounding or bias, or both.What this study addsWomen taking third generation oral contraceptives have a 1.7-fold increased risk of venous thrombosis compared with those taking second generation oral contraceptivesRisk is highest in first time usersThe biases were not large enough to account for the observed results
PMCID: PMC34722  PMID: 11463678
15.  Nomegestrol acetate-17b-estradiol for oral contraception 
Oral contraceptives remain a popular method of contraception over 50 years after their introduction. While safe and effective for many women, the failure rate of oral contraception is about 8%. Concerns about the risk of venous thromboembolism continue to drive the search for the safest oral contraceptive formulations. The oral contraceptive NOMAC-E2 contains nomegestrol acetate (NOMAC) 2.5 mg + 17b-estradiol (E2) 1.5 mg. The approved dosing regimen is 24 days of active hormone, followed by a 4-day hormone-free interval. NOMAC is a progestin derived from testosterone, which has high bioavailability, rapid absorption, and a long half-life. Estradiol, though it has a lower bioavailability, has been successfully combined with NOMAC in a monophasic oral contraceptive. Two recently published randomized controlled trials demonstrate that NOMAC-E2 is an effective contraceptive, with a Pearl Index less than one pregnancy per 100 woman-years. The bleeding pattern on NOMAC-E2 is characterized by fewer bleeding/spotting days, shorter withdrawal bleeds, and a higher incidence of amenorrhea than the comparator oral contraceptive containing drospirenone and ethinyl estradiol. The adverse event profile appears to be acceptable. Few severe adverse events were reported in the randomized controlled trials. The most common adverse events were irregular bleeding, acne, and weight gain. Preliminary studies suggest that NOMAC-E2 does not seem to have negative effects on hemostatic and metabolic parameters. While no one oral contraceptive formulation is likely to be the optimum choice for all women, NOMAC-E2 is a formulation with effectiveness comparable with that of other oral contraceptives, and a reassuring safety profile.
doi:10.2147/PPA.S39371
PMCID: PMC3702550  PMID: 23836965
oral contraception; nomegestrol acetate; estradiol
16.  Gallbladder disease and use of transdermal versus oral hormone replacement therapy in postmenopausal women: prospective cohort study 
Objective To determine whether transdermal compared with oral use of hormone replacement therapy reduces the risk of gallbladder disease in postmenopausal women.
Design Prospective cohort study (Million Women Study).
Setting Women registered with the National Health Service (NHS) in England and Scotland.
Participants 1 001 391 postmenopausal women (mean age 56) recruited between 1996 and 2001 from NHS breast screening centres and followed by record linkage to routinely collected NHS hospital admission data for gallbladder disease.
Main outcome measures Adjusted relative risk and standardised incidence rates of hospital admission for gallbladder disease or cholecystectomy according to use of hormone replacement therapy.
Results During follow-up 19 889 women were admitted for gallbladder disease; 17 190 (86%) had a cholecystectomy. Compared with never users of hormone replacement therapy, current users were more likely to be admitted for gallbladder disease (relative risk 1.64, 95% confidence interval 1.58 to 1.69) but risks were substantially lower with transdermal therapy than with oral therapy (relative risk 1.17, 1.10 to 1.24 v 1.74, 1.68 to 1.80; heterogeneity P<0.001). Among women using oral therapy, equine oestrogens were associated with a slightly greater risk of gallbladder disease than estradiol (relative risk 1.79, 1.72 to 1.87 v 1.62, 1.54 to 1.70; heterogeneity P<0.001) and higher doses of oestrogen increased the risk more than lower doses: for equine oestrogens >0.625 mg, 1.91 (1.78 to 2.04) v ≤0.625 mg, 1.76 (1.68 to 1.84); heterogeneity P=0.02; estradiol >1 mg, 1.68 (1.59 to 1.77) v ≤1 mg, 1.44 (1.31 to 1.59); heterogeneity P=0.003. The risk of gallbladder disease decreased with time since stopping therapy (trend P=0.004). Results were similar taking cholecystectomy as the outcome. Standardised hospital admission rates per 100 women over five years for cholecystectomy were 1.1 in never users, 1.3 with transdermal therapy, and 2.0 with oral therapy.
Conclusion Gallbladder disease is common in postmenopausal women and use of hormone replacement therapy increases the risk. Use of transdermal therapy rather than oral therapy over a five year period could avoid one cholecystectomy in every 140 users.
doi:10.1136/bmj.a386
PMCID: PMC2500203  PMID: 18617493
17.  Safety, efficacy, actions, and patient acceptability of drospirenone/ethinyl estradiol contraceptive pills in the treatment of premenstrual dysphoric disorder 
Premenstrual dysphoric disorder (PMDD) is estimated to affect 3%–8% of reproductive age women. Multiple therapeutic modalities have been evaluated with varying efficacy for the associated somatic and mood symptoms. The majority of older studies had shown that oral contraceptive pills (OCs) were most effective for the physical symptoms. However, newer OCs containing a novel progestin, drospirenone, have shown promise in alleviating both the somatic and affective/behavioral symptoms. This progestin, which is a derivative of spironolactone, has both antimineralocorticoid and antiandrogenic activity. A 24/4 formulation containing 20 μg of ethinyl estradiol has been found effective in randomized double-blind placebo-controlled trials utilizing established scales documenting symptoms associated with PMDD. Multiple studies have shown that drospirenone-containing OCs are safe without evidence of clinically adverse effects on carbohydrate metabolism, lipids, blood pressure, weight, serum potassium or increased thrombotic events compared to other low dose OCs. In addition, significant improvements have been demonstrated in acne, hirsutism, and fluid retention symptoms. Several open label studies demonstrated good patient compliance and reported satisfaction with the method. Because of the significant placebo effect demonstrated in the blinded placebo-controlled trials, additional large randomized placebo-controlled trials are needed to confirm the efficacy of the drospirenone OCs in the treatment of PMDD. However, this OC formulation appears to be a promising therapeutic modality.
PMCID: PMC2971718  PMID: 21072278
drospirenone; premenstrual dysphoric disorder; premenstrual syndrome; oral contraceptive pill
18.  Novel oral contraceptive for heavy menstrual bleeding: estradiol valerate and dienogest 
Abnormal uterine bleeding (AUB) is associated with significant direct medical costs and impacts both society and the quality of life for individual women. Heavy menstrual bleeding, a subset of AUB, also referred to as menorrhagia, is defined as menstrual blood loss greater than 80 mL or the patient’s perception of excessive blood loss. The newest treatment option available is a novel combination oral contraceptive product containing estradiol valerate (E2V) and dienogest (DNG). As with other combination oral contraceptives, E2V/DNG works primarily by preventing ovulation. However, in contrast with other combination oral contraceptives, it is the progestin component of E2V/DNG that is responsible for endometrial stabilization. Use of E2V/DNG for six months has led to significant reductions in heavy menstrual bleeding with an average 65% reduction in mean blood loss. Approximately half of the women with heavy menstrual bleeding who received E2V/DNG for six months demonstrated an 80% reduction in mean blood loss. Additionally, significant improvements in hematologic indicators (ie, ferritin, hemoglobin, and hematocrit) have been shown. Based on its chemical properties, E2V/DNG may have fewer adverse effects on lipid and glucose metabolism and reduced risk of thromboembolic complications compared with other combination oral contraceptives. This has not yet been shown in clinical trials and until then it should be assumed that E2V/DNG has a safety profile similar to other combination oral contraceptives containing 35 μg or less of ethinyl estradiol. E2V/DNG has been compared with another combination oral contraceptive in healthy women without heavy menstrual bleeding and demonstrated improved bleeding patterns. E2V/DNG has not been compared with the levonorgestrel intrauterine device or other treatments for heavy menstrual bleeding. When compared with some other treatment options for AUB, E2V/DNG provides the added advantage of effective contraception.
doi:10.2147/IJWH.S31922
PMCID: PMC3684222  PMID: 23788843
contraception; dienogest; estradiol valerate; Natazia®; menstrual disorders; menorrhagia
19.  Assessing the risk of venous thromboembolic events in women taking progestin-only contraception: a meta-analysis 
Objectives To evaluate the risk of venous thromboembolic events associated with the use of progestin-only contraception and whether that risk differs with the mode of drug delivery (oral, intrauterine, or depot injection).
Design Systematic review and meta-analysis of randomised controlled trials and observational studies.
Data sources Pubmed, Embase, Cochrane Library, and reference lists of relevant reviews.
Study selection Randomised controlled trials and case-control, cohort, and cross sectional studies with venous thromboembolic outcome for progestin-only contraception reported relative to a non-hormone comparator group.
Data extraction Data were extracted by two independent investigators, and consensus for inclusion was reached after assessment by additional investigators.
Results Among the 2022 unique references identified by all searches, eight observational studies fulfilled inclusion criteria. A total of 147 women across all studies were diagnosed with a venous thromboembolic event while taking progestin-only contraception, and the summary measure for the adjusted relative risk of a venous thromboembolic episode for users versus non-users of a progestin-only contraceptive was, based on the random effects model, 1.03 (95% CI 0.76 to 1.39). Subgroup analysis confirmed there was no association between venous thromboembolic risk and progestin-only pills (relative risk 0.90 (0.57 to 1.45)) or a progestin intrauterine device (0.61 (0.24 to 1.53)). The relative risk of a venous thromboembolic event for users of an injectable progestin versus non-users was 2.67 (1.29 to 5.53).
Conclusions Published data assessing the risk of venous thromboembolism in women prescribed progestin-only contraception are limited. In this meta-analysis of eight observational studies, the use of progestin-only contraception was not associated with an increased risk of venous thromboembolism compared with non-users of hormonal contraception. The potential association between injectable progestins and thrombosis requires further study.
doi:10.1136/bmj.e4944
PMCID: PMC3413580  PMID: 22872710
20.  Hormonal contraception and pelvic girdle pain during pregnancy: a population study of 91 721 pregnancies in the Norwegian Mother and Child Cohort 
Human Reproduction (Oxford, England)  2013;28(11):3134-3140.
STUDY QUESTION
Is pre-pregnancy hormonal contraception use associated with the development of pelvic girdle pain during pregnancy?
SUMMARY ANSWER
In contrast to combined oral contraceptive pills, long lifetime exposure to progestin-only contraceptive pills or the use of a progestin intrauterine device during the final year before pregnancy were associated with pelvic girdle pain.
WHAT IS ALREADY KNOWN
Pelvic girdle pain severely affects many women during pregnancy. Smaller studies have suggested that hormonal contraceptive use is involved in the underlying mechanisms, but evidence is inconclusive.
STUDY DESIGN, SIZE, DURATION
A population study during the years 1999–2008.
PARTICIPANTS/MATERIALS, SETTING, METHODS
A total of 91 721 pregnancies included in the Norwegian Mother and Child Cohort Study. Data were obtained by two self-administered questionnaires during pregnancy weeks 17 and 30.
MAIN RESULTS AND THE ROLE OF CHANCE
Pelvic girdle pain was present in 12.9% of women who had used combined oral contraceptive pills during the last pre-pregnancy year, 16.4% of women who had used progestin-only contraceptive pills, 16.7% of women who had progestin injections and 20.7% of women who had used progestin intrauterine devices, compared with 15.3% of women who did not report use of hormonal contraceptives. After adjustment for other study factors, the use of a progestin intrauterine device was the only factor based on the preceding year associated with pelvic girdle pain [adjusted odds ratios (OR) 1.20; 95% confidence interval (CI): 1.11–1.31]. Long lifetime exposure to progestin-only contraceptive pills was also associated with pelvic girdle pain (adjusted OR 1.49; 95% CI: 1.01–2.20).
LIMITATIONS, REASONS FOR CAUTION
The participation rate was 38.5%. However, a recent study on the potential biases of skewed selection in the Norwegian Mother and Child Cohort Study found the prevalence estimates but not the exposure-outcome associations to be influenced by the selection.
WIDER IMPLICATIONS OF THE FINDINGS
The results suggest that combined oral contraceptives can be used without fear of developing pelvic girdle pain during pregnancy. However, the influence of progestin intrauterine devices and long-term exposure to progestin-only contraceptive pills requires further study.
STUDY FUNDING/COMPETING INTEREST(S)
The present study was supported by the Norwegian Research Council. None of the authors has a conflict of interest.
doi:10.1093/humrep/det301
PMCID: PMC3795467  PMID: 23887071
hormonal contraception; pelvic girdle pain; pregnancy; risk factors; the Norwegian Mother and Child Cohort Study
21.  Venous thrombosis in users of non-oral hormonal contraception: follow-up study, Denmark 2001-10 
Objective To assess the risk of venous thrombosis in current users of non-oral hormonal contraception.
Design Historical national registry based cohort study.
Setting Four national registries in Denmark.
Participants All Danish non-pregnant women aged 15-49 (n=1 626 158), free of previous thrombotic disease or cancer, were followed from 2001 to 2010.
Main outcome measures Incidence rate of venous thrombosis in users of transdermal, vaginal, intrauterine, or subcutaneous hormonal contraception, relative risk of venous thrombosis compared with non-users, and rate ratios of venous thrombosis in current users of non-oral products compared with the standard reference oral contraceptive with levonorgestrel and 30-40 µg oestrogen. Diagnoses were confirmed by at least four weeks of anticoagulation therapy after the diagnosis.
Results Within 9 429 128 woman years of observation, 5287 first ever venous thrombosis events were recorded, of which 3434 were confirmed. In non-users of hormonal contraception the incidence rate of confirmed events was 2.1 per 10 000 woman years. Compared with non-users of hormonal contraception, and after adjustment for age, calendar year, and education, the relative risk of confirmed venous thrombosis in users of transdermal combined contraceptive patches was 7.9 (95% confidence interval 3.5 to 17.7) and of the vaginal ring was 6.5 (4.7 to 8.9). The corresponding incidences per 10 000 exposure years were 9.7 and 7.8 events. The relative risk was increased in women who used subcutaneous implants (1.4, 0.6 to 3.4) but not in those who used the levonorgestrel intrauterine system (0.6, 0.4 to 0.8). Compared with users of combined oral contraceptives containing levonorgestrel, the adjusted relative risk of venous thrombosis in users of transdermal patches was 2.3 (1.0 to 5.2) and of the vaginal ring was 1.9 (1.3 to 2.7).
Conclusion Women who use transdermal patches or vaginal rings for contraception have a 7.9 and 6.5 times increased risk of confirmed venous thrombosis compared with non-users of hormonal contraception of the same age, corresponding to 9.7 and 7.8 events per 10 000 exposure years. The risk was slightly increased in women using subcutaneous implants but not in those using the levonorgestrel intrauterine system.
doi:10.1136/bmj.e2990
PMCID: PMC3349780  PMID: 22577198
22.  The risk of serious illness among oral contraceptive users: evidence from the RCGP's oral contraceptive study. 
The British Journal of General Practice  1998;48(435):1657-1662.
BACKGROUND: So far, no-one has attempted to evaluate the overall balance of serious, but not necessarily fatal, disease among a cohort of oral contraceptive users. AIM: To emprirically assess the balance of risk of serious illness among a cohort of oral contraceptive users followed up for up to 28 years. METHODS: Oral contraceptive-associated serious disease was defined as that which is often life-threatening and/or associated with long-term disability, and which has been found, or postulated, to be associated with use of combined oral contraceptives. Data from the Royal College of General Practitioners' (RCGP) Oral Contraception Study were examined to determine the rate of such conditions during 335,181 woman-years of observation in 'ever users' and 228,727 woman-years in 'never users'. The rates were standardized for age, parity, social class, and smoking. RESULTS: Compared with never users, ever users had a small increased risk of any serious disease (relative risk = 1.17; 95% confidence interval = 1.09-1.25). Ever users had an excess risk of cerebrovascular disease, pulmonary embolism, and venous thromboembolism, and reduced risk of ovarian and endometrial cancer. The increased risk was seen only in younger women; by the age of 50, ever users had the same risk as never users. The risk appeared to be confined to women using older oral contraceptives containing 50 micrograms or more of oestrogen. CONCLUSIONS: Past users of older, higher dose oral contraceptives can be reassured that the small increased risk of serious disease seen during current use does not persist after stopping, and that latent effects do not appear later in life. Currently available oral contraceptives, containing less than 50 micrograms of oestrogen accompanied by the progestogen, levonorgestrel, or norethisterone acetate, do not appear to be associated with an increased net risk of serious disease.
PMCID: PMC1313240  PMID: 10071398
23.  ORAL CONTRACEPTIVE USE AND BREAST CANCER: A PROSPECTIVE STUDY OF YOUNG WOMEN 
Background
Previous studies convincingly showed an increase in risk of breast cancer associated with current or recent use of oral contraceptives in the 1960’s to 1980’s. The relation of contemporary oral contraceptive formulations to breast cancer risk is less clear.
Methods
We assessed lifetime oral contraceptive use and the specific formulations used among 116,608 female nurses aged 25 to 42 years at enrollment in 1989, and subsequently updated this information every two years. We related this information to risk of breast cancer up to June 1, 2001.
Results
During 1,246,967 person-years of follow-up, 1,344 cases of invasive breast cancer were diagnosed. Past use of any oral contraceptive was not related to breast cancer risk (multivariate relative risk, 1.12; 95 percent confidence interval 0.95–1.33). Current use of any oral contraceptive was related to a marginally significant higher risk (multivariate relative risk, 1.33; 95 percent confidence interval 1.03–1.73). One specific formulation substantially accounted for the excess risk: the relative risk for current use of triphasic preparations with levonorgestrel as the progestin was 3.05 (95 percent confidence interval, 2.00–4.66, P<0.0001).
Conclusions
Current use of oral contraceptives carries an excess risk of breast cancer. Levonorgestrel used in triphasic preparations may account for much of this elevation in risk.
Impact
Different oral contraceptive formulations may convey different risks of breast cancer; ongoing monitoring of these associations is necessary as oral contraceptive formulations change.
doi:10.1158/1055-9965.EPI-10-0747
PMCID: PMC3055790  PMID: 20802021
breast cancer; oral contraceptives; progestins
24.  Third generation oral contraceptives and risk of venous thromboembolic disorders: an international case-control study. Transnational Research Group on Oral Contraceptives and the Health of Young Women. 
BMJ : British Medical Journal  1996;312(7023):83-88.
OBJECTIVE--To test whether use of combined oral contraceptives containing third generation progestogens is associated with altered risk of venous thromboembolism. DESIGN--Matched case-control study. SETTING--10 centres in Germany and United Kingdom. SUBJECTS--Cases were 471 women aged 16-44 who had a venous thromboembolism. Controls were 1772 women (at least 3 controls per case) unaffected by venous thromboembolism who were matched with corresponding case for age and for hospital or community setting. MAIN OUTCOME MEASURES--Odds ratios derived with stratified analyses and unconditional logistic regression to adjust for potential confounding variables. RESULTS--Odds ratios (95% confidence intervals) for venous thromboembolism were: for any oral contraceptives versus no use, 4.0 (3.1 to 5.3); for second generation products (low dose ethinyl-oestradiol, no gestodene or desogestrel) versus no use, 3.2 (2.3 to 4.3); for third generation products (low dose ethinyloestradiol, gestodene or desogestrel) versus no use, 4.8 (3.4 to 6.7); for third generation products versus second generation products, 1.5 (1.1 to 2.1); for products containing gestodene versus second generation products, 1.5 (1.0 to 2.2); and for products containing desogestrel versus second generation products, 1.5 (1.1 to 2.2). Probability of death due to venous thromboembolism for women using third generation products is about 20 per million users per year, for women using second generation products it is about 14 per million users per year, and for non-users it is five per million per year. CONCLUSIONS--Risk of venous thromboembolism was slightly increased in users of third generation oral contraceptives compared with users of second generation products.
PMCID: PMC2349742  PMID: 8555935
25.  Combining oral contraceptives with a natural nuclear factor-kappa B inhibitor for the treatment of endometriosis-related pain 
Endometriosis is a chronic disease in which a persistent state of heightened inflammation is maintained by nuclear factor-kappa B (NF-κB) activation. The progestins present in oral contraceptives are potent inhibitors of NF-κB translocation to cell nuclei, while Pycnogenol® (Pinus pinaster) acts by blocking post-translational events. In this study, the effects of Pycnogenol on pain scores were investigated in patients with endometriosis using oral contraceptives containing either gestodene or drospirenone in extended regimens. Pain scores were determined using a visual analog scale before and after 3 months of treatment. Oral contraceptives, used alone (groups 1 and 3) or in association with Pycnogenol (groups 2 and 4), resulted in significant decreases in pain scores after 3 months of treatment; however, this reduction was significantly greater in the groups using oral contraceptives + Pycnogenol (groups 2 and 4) compared with those using oral contraceptives alone (groups 1 and 3). In the groups using oral contraceptives alone, 50% of patients became pain-free by the end of the third month of treatment. These results suggest that Pycnogenol increases the efficacy of oral contraceptives for the treatment of endometriosis-related pain.
doi:10.2147/IJWH.S55210
PMCID: PMC3873204  PMID: 24379702
Pycnogenol®; aromatase; endometriosis; nuclear factor-kappa B

Results 1-25 (1168971)