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1.  Forceps Delivery Volumes in Teaching and Nonteaching Hospitals: Are Volumes Sufficient for Physicians to Acquire and Maintain Competence? 
The decline in the use of forceps in operative deliveries over the last two decades raises questions about teaching hospitals' ability to provide trainees with adequate experience in the use of forceps. The authors examined: (1) the number of operative deliveries performed in teaching and nonteaching hospitals, and (2) whether teaching hospitals performed a sufficient number of forceps deliveries for physicians to acquire and maintain competence.
The authors used State Inpatient Data from nine states to identify all women hospitalized for childbirth in 2008. They divided hospitals into three categories: major teaching, minor teaching, and nonteaching. They calculated delivery volumes (total operative, cesarean, vacuum, forceps, two or more methods) for each hospital and compared data across hospital categories.
The sample included 1,344,305 childbirths in 835 hospitals. The mean cesarean volumes for major teaching, minor teaching, and nonteaching hospitals were 969.8, 757.8, and 406.9. The mean vacuum volumes were 301.0, 304.2, and 190.4, and the mean forceps volumes were 25.2, 15.3, and 8.9. In 2008, 31 hospitals (3.7% of all hospitals) performed no vacuum extractions, and 320 (38.3%) performed no forceps deliveries. In 2008, 13 (23%) major teaching and 44 (44%) minor teaching hospitals performed five or fewer forceps deliveries.
Low forceps delivery volumes may preclude many trainees from acquiring adequate experience and proficiency. These findings highlighted broader challenges, faced by many specialties, in ensuring that trainees and practicing physicians acquire and maintain competence in infrequently performed, highly technical procedures.
PMCID: PMC4317267  PMID: 24280847
2.  Diversity of the Vaginal Microbiome Correlates With Preterm Birth 
Reproductive Sciences  2014;21(1):32-40.
Reproductive tract infection is a major initiator of preterm birth (PTB). The objective of this prospective cohort study of 88 participants was to determine whether PTB correlates with the vaginal microbiome during pregnancy. Total DNA was purified from posterior vaginal fornix swabs during gestation. The 16S ribosomal RNA gene was amplified using polymerase chain reaction primers, followed by chain-termination sequencing. Bacteria were identified by comparing contig consensus sequences with the Ribosomal Database Project. Dichotomous responses were summarized via proportions and continuous variables via means ± standard deviation. Mean Shannon Diversity index differed by Welch t test (P = .00016) between caucasians with PTB and term gestation. Species diversity was greatest among African Americans (P = .0045). Change in microbiome/Lactobacillus content and presence of putative novel/noxious bacteria did not correlate with PTB. We conclude that uncultured vaginal bacteria play an important role in PTB and race/ethnicity and sampling location are important determinants of the vaginal microbiome.
PMCID: PMC3857766  PMID: 23715799
PTB; vaginal microbiome; race/ethnicity
3.  Association Between Vaginal Birth After Cesarean Delivery and Primary Cesarean Delivery Rates 
Obstetrics and gynecology  2013;122(5):1010-1017.
To estimate the association between vaginal birth after cesarean delivery (VBAC) rates and primary cesarean delivery rates in California hospitals.
Hospital VBAC rates were calculated using birth certificate and discharge data from 2009, and hospitals were categorized by quartile of VBAC rate. Multivariable logistic regression analysis was performed to estimate the odds of cesarean delivery among low-risk nulliparous women with singleton pregnancies at term in vertex presentation (nulliparous term singleton vertex) by hospital VBAC quartile while controlling for many patient-level and hospital-level confounders.
There were 468,789 term singleton births in California in 2009 at 255 hospitals, 125,471 of which were low-risk nulliparous term singleton vertex. Vaginal birth after cesarean delivery rates varied between hospitals, with a range of 0–44.6%. Rates of cesarean delivery among low-risk nulliparous term singleton vertex women declined significantly with increasing VBAC rate. When adjusted for maternal and hospital characteristics, low-risk nulliparous term singleton vertex women who gave birth in hospitals in the highest VBAC quartile had an odds ratio of 0.55 (95% confidence interval 0.46–0.66) of cesarean delivery compared with women at hospitals with the lowest VBAC rates. Each percentage point increase in a hospital’s VBAC rate was associated with a 0.65% decrease in the low-risk nulliparous term singleton vertex cesarean delivery rate.
Hospitals with higher rates of VBAC have lower rates of primary cesarean delivery among low-risk nulliparous women with singleton pregnancies at term in vertex presentation.
PMCID: PMC4199326  PMID: 24104780
4.  Economic downturns and male cesarean deliveries: a time-series test of the economic stress hypothesis 
In light of the recent Great Recession, increasing attention has focused on the health consequences of economic downturns. The perinatal literature does not converge on whether ambient economic declines threaten the health of cohorts in gestation. We set out to test the economic stress hypothesis that the monthly count of cesarean deliveries (CD), which may gauge the level of fetal distress in a population, rises after the economy declines. We focus on male CD since the literature reports that male more than female fetuses appear sensitive to stressors in utero.
We tested our ecological hypothesis in California for 228 months from January 1989 to December 2007, the most recent data available to us at the time of our tests. We used as the independent variable the Bureau of Labor Statistics unadjusted total state employment series. Time-series methods controlled for patterns of male CD over time. We also adjusted for the monthly count of female CD, which controls for well-characterized factors (e.g., medical-legal environment, changing risk profile of births) that affect CD but are shared across infant sex.
Findings support the economic stress hypothesis in that male CD increases above its expected value one month after employment declines (employment coefficient = -24.09, standard error = 11.88, p = .04). Additional exploratory analyses at the metropolitan level indicate that findings in Los Angeles and Orange Counties appear to drive the State-level relation.
Contracting economies may perturb the health of male more than female fetuses sufficiently enough to warrant more CD. Male relative to female CD may sensitively gauge the cohort health of gestations.
PMCID: PMC4059074  PMID: 24906208
Cesarean delivery; Economic stress; Fetal distress; Male sensitivity
5.  The Cost-Effectiveness of Repeat HIV Testing During Pregnancy in a Resource-Limited Setting 
To estimate the cost-effectiveness of HIV screening strategies for the prevention of perinatal transmission in Uganda, a resource-limited country with high HIV prevalence and incidence.
We designed a decision-analytic model from a health care system perspective to assess the vertical transmission rates and cost-effectiveness of four different HIV screening strategies in pregnancy: 1) Rapid HIV antibody (Ab) test at initial visit (current standard of care); 2) Strategy 1 + HIV RNA at initial visit (adds detection of acute HIV); 3) Strategy 1 + repeat HIV Ab at delivery (adds detection of incident HIV); 4) Strategy 3 + HIV RNA at delivery (adds detection of acute HIV at delivery). Model estimates were derived from the literature and local sources, and life years saved were discounted at a rate of 3% per year. Based on World Health Organization guidelines, we defined our cost-effectiveness threshold as ≤3 times the gross domestic product per capita, which for Uganda was US$3300 in 2008.
Using base case estimates of 10% HIV prevalence among women entering prenatal care and 3% incidence during pregnancy, strategy 3 was incrementally the cost-effective option that led to the greatest total life years.
Repeat rapid HIV Ab testing at the time of labor is a cost-effective strategy even in a resource-limited setting such as Uganda.
PMCID: PMC3653987  PMID: 23392461
HIV; pregnancy; perinatal transmission; decision analysis; cost-effectiveness analysis
6.  Gestational weight loss and perinatal outcomes in overweight and obese women subsequent to diagnosis of gestational diabetes mellitus 
Obesity (Silver Spring, Md.)  2013;21(12):10.1002/oby.20490.
To investigate whether gestational weight loss after the diagnosis of gestational diabetes mellitus (GDM) in overweight and obese women is associated with improved perinatal outcomes. Obesity and GDM are risk factors for adverse perinatal outcomes, but few studies have investigated weight loss during pregnancy in women with these comorbidities.
Retrospective cohort study of 26,205 overweight and obese gestational diabetic women enrolled in the California Diabetes and Pregnancy Program. Women with gestational weight loss (GWL) during program enrollment were compared to those with weight gain. Perinatal outcomes were assessed using chi-square test and multivariable logistic regression analysis. RESULTS: 5.2% of women experienced GWL. GWL was associated with decreased odds of macrosomia (aOR 0.63, 95% CI 0.52–0.77), NICU admission (aOR 0.51, 95% CI 0.27–0.95), and cesarean delivery (aOR 0.81, 95% CI 0.68–0.97). Odds of SGA status (aOR 1.69, 95% CI 1.32–2.17) and preterm delivery <34 weeks (aOR 1.71, 95% CI 1.23–2.37) were increased.
In overweight and obese women with GDM, third trimester weight loss is associated with some improved maternal and neonatal outcomes, although this effect is lessened by increased odds of SGA status and preterm delivery. We recommend further research on weight loss and interventions to improve adherence to weight guidelines in this population.
PMCID: PMC3758809  PMID: 23613187
obesity; pregnancy; gestational diabetes; gestational weight loss; pregnancy outcomes
7.  Elective Induction of Labor at Term Compared With Expectant Management 
Obstetrics and gynecology  2013;122(4):761-769.
To test the association of elective induction of labor at term compared with expectant management and maternal and neonatal outcomes.
This was a retrospective cohort study of all deliveries without prior cesarean delivery in California in 2006 using linked hospital discharge and vital statistics data. We compared elective induction at each term gestational age (37–40 weeks) as defined by The Joint Commission with expectant management in vertex, non-anomalous, singleton deliveries. We used multivariable logistic regression to test the association of elective induction and cesarean delivery, operative vaginal delivery, maternal third- or fourth-degree lacerations, perinatal death, neonatal intensive care unit admission, respiratory distress, shoulder dystocia, hyperbilirubinemia, and macrosomia (birth weight greater than 4,000 g) at each gestational week, stratified by parity.
The cesarean delivery rate was 16%, perinatal mortality was 0.2%, and neonatal intensive care unit admission was 6.2% (N=362,154). The odds of cesarean delivery were lower among women with elective induction compared with expectant management across all gestational ages and parity (37 weeks [odds ratio (OR) 0.44, 95% confidence interval (CI) 0.34–0.57], 38 weeks [OR 0.43, 95% CI 0.38–0.50], 39 weeks [OR 0.46, 95% CI 0.41–0.52], 40 weeks [OR 0.57, CI 0.50–0.65]). Elective induction was not associated with increased odds of severe lacerations, operative vaginal delivery, perinatal death, neonatal intensive care unit admission, respiratory distress, shoulder dystocia, or macrosomia at any term gestational age. Elective induction was associated with increased odds of hyperbilirubinemia at 37 and 38 weeks of gestation and shoulder dystocia at 39 weeks of gestation.
Elective induction of labor is associated with decreased odds of cesarean delivery when compared with expectant management
PMCID: PMC3905733  PMID: 24084532
8.  The Effect of Maternal Body Mass Index on Perinatal Outcomes in Women with Diabetes 
American journal of perinatology  2013;31(3):249-256.
To determine the effect of increasing maternal obesity, including superobesity (body mass index [BMI] ≥ 50 kg/m2), on perinatal outcomes in women with diabetes.
Study Design
Retrospective cohort study of birth records for all live-born nonanom-alous singleton infants ≥ 37 weeks’ gestation born to Missouri residents with diabetes from 2000 to 2006. Women with either pregestational or gestational diabetes were included.
There were 14,595 births to women with diabetes meeting study criteria, including 7,082 women with a BMI > 30 kg/m2 (48.5%). Compared with normal-weight women with diabetes, increasing BMI category, especially superobesity, was associated with a significantly increased risk for preeclampsia (adjusted relative risk [aRR] 3.6, 95% confidence interval [CI] 2.5, 5.2) and macrosomia (aRR 3.0, 95% CI 1.8, 5.40). The majority of nulliparous obese women with diabetes delivered via cesarean including 50.5% of obese, 61.4% of morbidly obese, and 69.8% of superobese women. The incidence of primary elective cesarean among nulliparous women with diabetes increased significantly with increasing maternal BMI with over 33% of morbidly obese and 39% of superobese women with diabetes delivering electively by cesarean.
Increasing maternal obesity in women with diabetes is significantly associated with higher risks of perinatal complications, especially cesarean delivery.
PMCID: PMC3852172  PMID: 23696430
cesarean; diabetes; obesity; superobesity
9.  Racial disparities in pregnancy outcomes in obese women 
To estimate the effect of race on perinatal outcomes in obese women.
Retrospective cohort study of birth records linked to hospital discharge data for all live born singleton infants ≥37 weeks gestation born to African-American or Caucasian Missouri residents from 2000 to 2006. We excluded major congenital anomalies and women with diabetes or chronic hypertension. Obesity was defined as pre-pregnancy body mass index ≥30 kg/m2.
There were 312 412 births meeting study criteria. 27.1% (11 776) of African-American mothers and 19.1% (49 415) of Caucasian mothers were obese. There were no differences in cesarean delivery or preeclampsia between obese African-American and obese Caucasian women. Infants of obese African-American women were significantly less likely to be macrosomic (0.9% vs. 2.2%, adjusted odds ratio [aOR] 0.5, 95% confidence interval [CI] 0.4 0.6) and more likely to be low birth weight (3.4% vs. 1.8%, aOR 1.9, 95% CI 1.7, 2.2) compared to infants of obese Caucasian women. Compared to their normal weight peers, obese Caucasian women had a greater relative risk of developing preeclampsia (aOR 3.1, 95% CI 2.9, 3.2) than obese African-American women (aOR 2.1, 95% CI 1.9, 2.4).
Racial disparities impact obesity-related maternal and neonatal complications of pregnancy.
PMCID: PMC3864564  PMID: 23682611
Obesity; perinatal outcomes; race; racial disparities
10.  Obesity Trends and Perinatal Outcomes in Black and White Teenagers 
Our objective was to explore the trends in prepregnancy BMI for Black and White teenagers over time and the association between elevated BMI and outcomes based on race.
Study Design
This was a retrospective cohort study of singleton infants (n=38,158) born to Black (34%) and White teenagers (< 18 years of age). We determined the prevalence of elevated prepregnancy BMI between 1993 and 2006 and the association between elevated prepregnancy BMI (primary exposure) and maternal and perinatal outcomes based on race (2000–2006).
The percent of White teenagers with elevated prepregnancy BMI increased significantly from 17% to 26%. White and Black overweight and obese teenagers were more likely to have pregnancy-related hypertension than normal weight teenagers while postpartum hemorrhage was only increased in obese Black teenagers and infant complications only in overweight and obese White teenagers.
As the percent of elevated prepregnancy BMI has increased in White teenagers, specific risks for poor maternal and perinatal outcomes in the overweight and obese teenagers varies by race.
PMCID: PMC3569854  PMID: 23174388
Adolescents; Obesity; Outcomes
11.  The Association Between Hospital Obstetric Volume and Perinatal Outcomes in California 
To analyze the association between hospital obstetric volume and perinatal outcomes in California.
Study Design
This was a retrospective cohort study of births occurring in California in 2006. Hospitals were divided into four obstetric volume categories. Unadjusted rates of neonatal mortality and birth asphyxia were calculated for each category, overall and among term deliveries with birthweight >2500g. Multivariable logistic regression was used to control for confounders. Deliveries in rural hospitals were analyzed separately using different volume categories.
Prevalence of asphyxia increased with decreasing hospital volume overall and among term, non-low-birthweight infants, from 9 per 10,000 live births at highest-volume hospitals to 18/10,000 live births at the lowest-volume hospitals (p<0.001). Similar trends were observed in rural hospitals, with rates increasing from 7 to 34 per 10,000 live births in low-volume rural hospitals (p<0.001).
These findings provide evidence for an inverse association between hospital obstetric volume and birth asphyxia.
PMCID: PMC3516613  PMID: 23174387
Asphyxia; health facility size; healthcare systems; neonatal mortality
12.  The Effect of Race/Ethnicity on Adverse Perinatal Outcomes among Patients with Gestational Diabetes 
To determine racial/ethnic differences in perinatal outcomes among women with gestational diabetes mellitus (GDM).
Retrospective cohort study of 32,193 singleton births among GDMs in California from 2006, using Vital Statistics Birth and Death Certificate and Patient Discharge Data. Women were divided by race/ethnicity: White, Black, Hispanic, or Asian. Multivariable logistic regression analyzed associations between race/ethnicity and adverse outcomes, controlling for potential confounders. Outcomes included: primary cesarean, preeclampisa, neonatal hypoglycemia, preterm delivery, macrosomia, fetal anomaly, respiratory distress syndrome (RDS).
Compared to other races, Black women had higher odds of preeclampsia [aOR=1.57, 95%CI(1.47-1.95)], neonatal hypoglycemia [aOR=1.79, 95%CI(1.07-3.00)], and preterm delivery <37 weeks [aOR=1.56, 95%CI(1.33-1.83)]. Asians had the lowest odds of primary cesarean [aOR=0.75, 95%CI(0.69-0.82)], large for gestational age infants [aOR=0.40, 95%CI(0.33-0.48)], and neonatal RDS [aOR=0.54, 95%CI(0.40-0.73)].
Perinatal outcomes among women with GDM differ by race/ethnicity and may be attributed to inherent sociocultural differences that may impact glycemic control, the development of chronic co-morbidities, genetic variability, and variation in access to as well as quantity and quality of prenatal care.
PMCID: PMC3462223  PMID: 22818875
Gestational Diabetes; Perinatal Outcomes; Race/Ethnicity
13.  Effect of revised IOM weight gain guidelines on perinatal outcomes 
We sought to examine perinatal outcomes in women with a body mass index (BMI) of 25 kg/m2 comparing those whose weight gain met 2009 IOM guidelines to women meeting 1990 IOM guidelines.
This is a retrospective cohort study utilizing birth records linked to hospital discharge data for all term, singleton infants born to overweight, Missouri residents (2000–2006) with a BMI of 25 kg/m2. We excluded congenital anomalies, mothers with diabetes, hypertension, or previous cesarean delivery.
Fourteen thousand nine hundred fifty-five women gained 25–35 lbs (1990 guidelines); 1.6% delivered low birth weight (LBW) infants and 1.1% delivered macrosomic infants. Eight thousand three hundred fifty women gained 15–25 lbs (2009 guidelines); 3.4% delivered LBW infants and 0.6% delivered macrosomic infants. Women who gained 15–25 lbs were 1.99 (95% CI 1.67, 2.38) times more likely to have a LBW infant and 0.59 (95% CI 0.40, 0.76) times less likely to deliver a macrosomic infant.
Limiting weight gain in women with a BMI of 25 kg/m2, per the 2009 guidelines, increases the risk of LBW deliveries and decreases the risk of macrosomia but does not reduce associated adverse perinatal outcomes. Further studies should explore the optimal weight gain to reduce these outcomes.
PMCID: PMC3771357  PMID: 20593973
Gestational weight gain; infant outcomes
14.  Clinical utility and cost of non-invasive prenatal testing with cfDNA analysis in high-risk women based on a US population 
Evaluate the clinical and economic consequences of fetal trisomy 21 (T21) screening with non-invasive prenatal testing (NIPT) in high-risk pregnant women.
Using a decision-analytic model, we estimated the number of T21 cases detected, the number of invasive procedures performed, corresponding euploid fetal losses and total costs for three screening strategies: first trimester combined screening (FTS), integrated screening (INT) or NIPT, whereby NIPT was performed in high-risk patients (women 35 years or older or women with a positive conventional screening test). Modeling was based on a 4 million pregnant women cohort in the US.
NIPT, at a base case price of $795, was more clinically effective and less costly (dominant) over both FTS and INT. NIPT detected 4823 T21 cases based on 5330 invasive procedures. FTS detected 3364 T21 cases based on 108 364 procedures and INT detected 3760 cases based on 108 760 procedures. NIPT detected 28% and 43% more T21 cases compared to INT and FTS, respectively, while reducing invasive procedures by >95% and reducing euploid fetal losses by >99%. Total costs were $3786M with FTS, $3919M with INT and $3403M with NIPT.
NIPT leads to improved T21 detection and reduction in euploid fetal loss at lower total healthcare expenditures.
PMCID: PMC3741020  PMID: 23356557
Aneuploidy screening; cell-free DNA; cost-effectiveness; Down syndrome; non-invasive prenatal testing; trisomy 21
15.  The impact of chronic hypertension and pregestational diabetes on pregnancy outcomes 
The objective of the study was to examine the impact of chronic hypertension and pregestational diabetes on pregnancy outcomes.
This was a retrospective cohort study of 532,088 women undergoing singleton births in California in 2006. Women were categorized into chronic hypertension, pregestational diabetes, both, or neither. Pregnancy outcomes were compared using the χ2 test and multivariable logistic regression to control for potential confounders.
We identified differences in perinatal outcomes between the groups. The rate of preterm birth in women with both conditions was 35.5% versus 25.5% in women with chronic hypertension versus 19.4% in women with pregestational diabetes (P < .001). The rate of small for gestational age was 18.2% in women with both versus 18.3% in women with chronic hypertension versus 9.7% in women with pre-gestational diabetes (P <.001).
The impact of having both chronic hypertension and pregestational diabetes in pregnancy varies, depending on the outcome examined. Although some had an additive effect (eg, stillbirth), others did not (eg, preeclampsia).
PMCID: PMC3724349  PMID: 22892187
chronic hypertension; perinatal outcomes; pregestational diabetes
16.  The risk of intrauterine fetal death in the small-for-gestational-age fetus 
We sought to evaluate the risk of intrauterine fetal death (IUFD) in small-for-gestational-age (SGA) fetuses.
We analyzed a retrospective cohort of all births in the United States in 2005, as recorded in a national database. We calculated the risk of IUFD within 3 sets of SGA threshold categories as well as within non-SGA pregnancies using the number of at-risk fetuses as the denominator.
The risk of IUFD increased with gestational age and was inversely proportional to percentile of birthweight for gestational age. The risk for IUFD in those <3rd percentile was as high as 58.0 IUFDs per 10,000 at-risk fetuses, 43.9 for <5th percentile, and 26.3 for <10th percentile compared to 5.1 for non-SGA gestations.
There is an increase in the risk of IUFD in SGA fetuses compared to non-SGA fetuses at all gestational ages with the greatest risk demonstrated in the lowest percentile cohort evaluated.
PMCID: PMC3724359  PMID: 23021697
birthweight; fetal death; small for gestational age; stillbirth
17.  Risk of Stillbirth and Infant Death Stratified by Gestational Age 
Obstetrics and gynecology  2012;120(1):76-82.
To estimate the multiple dimensions of risk faced by pregnant women and their health care providers when comparing the risks of stillbirth at term with the risk of infant death after birth.
This is a retrospective cohort study that included all nonanomalous, term deliveries in the state of California from 1997 to 2006 (N=3,820,826). The study compared infant mortality rates after delivery at each week of term pregnancy with the rates of a composite fetal–infant mortality that would occur after expectant management for 1 additional week.
The risk of stillbirth at term increases with gestational age from 2.1 per 10,000 ongoing pregnancies at 37 weeks of gestation up to 10.8 per 10,000 ongoing pregnancies at 42 weeks of gestation. At 38 weeks of gestation, the risk of expectant management carries a similar risk of death as delivery, but at each later gestational age, the mortality risk of expectant management is higher than the risk of delivery (39 weeks of gestation: 12.9 compared with 8.8 per 10,000; 40 weeks of gestation: 14.9 compared with 9.5 per 10,000; 41 weeks of gestation: 17.6 compared with 10.8 per 10,000).
Infant mortality rates at 39, 40, and 41 weeks of gestation are lower than the overall mortality risk of expectant management for 1 week.
PMCID: PMC3719843  PMID: 22914394
18.  Induction of labor compared to expectant management in low-risk women and associated perinatal outcomes 
We sought to examine the association of labor induction and perinatal outcomes.
This was a retrospective cohort study of low-risk nulliparous women with term, live births. Women who had induction at a given gestational age (eg, 39 weeks) were compared to delivery at a later gestation (eg, 40, 41, or 42 weeks).
Compared to delivery at a later gestational age, those induced at 39 weeks had a lower risk of cesarean (adjusted odds ratio [aOR], 0.90; 95% confidence interval [CI], 0.88–0.91) and labor dystocia (aOR, 0.88; 95% CI, 0.84–0.94). Their neonates had lowered risk of having 5-minute Apgar <7 (aOR, 0.81; 95% CI, 0.72–0.92), meconium aspiration syndrome (aOR, 0.30; 95% CI, 0.19–0.48), and admission to neonatal intensive care unit (aOR, 0.87; 95% CI, 0.78–0.97). Similar findings were seen for women who were induced at 40 weeks compared to delivery later.
Induction of labor in low-risk women at term is not associated with increased risk of cesarean delivery compared to delivery later.
PMCID: PMC3719847  PMID: 23063017
cesarean; induction; neonatal outcomes
19.  The Association between Body Mass Index and Gestational Diabetes Mellitus Varies by Race/Ethnicity 
American journal of perinatology  2011;28(7):515-520.
We examined body mass index (BMI) as a screening tool for gestational diabetes (GDM) and its sensitivity among different racial/ethnic groups. In a retrospective cohort study of 24,324 pregnant women at University of California, San Francisco, BMI was explored as a screening tool for GDM and was stratified by race/ethnicity. Sensitivity and specificity were examined using chi-square test and receiver-operator characteristic curves. BMI of ≥25.0 kg/m2 as a screening threshold identified GDM in >76% of African-Americans, 58% of Latinas, and 46% of Caucasians, but only 25% of Asians (p<0.001). Controlling for confounders and comparing to a BMI of ≤25, African-Americans had the greatest increased risk of GDM (adjusted odds ratio [AOR] 5.1, 95% confidence interval [CI]: 3.0 to 8.5), followed by Caucasians (AOR 3.6, 95% CI: 2.7 to 4.8), Latinas (AOR 2.7, 95% CI: 1.9 to 3.8), and Asians (AOR 2.3, 95% CI: 1.8 to 3.0). BMI’s screening characteristics to predict GDM varied by race/ethnicity. BMI can be used to counsel regarding the risk of developing GDM, but alone it is not a good screening tool.
PMCID: PMC3666587  PMID: 21404165
Body mass index; gestational diabetes mellitus; glucose loading test; race/ethnicity; receiver-operator characteristic curve
20.  Maternal superobesity and perinatal outcomes 
The purpose of this study was to determine the effect of maternal superobesity (body mass index [BMI], ≥50 kg/m2) compared with morbid obesity (BMI, 40–49.9 kg/m2) or obesity (BMI, 30–39.9 kg/m2) on perinatal outcomes.
We conducted a retrospective cohort study of birth records that were linked to hospital discharge data for all liveborn singleton term infants who were born to obese Missouri residents from 2000–2006. We excluded major congenital anomalies and women with diabetes mellitus or chronic hypertension.
There were 64,272 births that met the study criteria, which included 1185 superobese mothers (1.8%). Superobese women were significantly more likely than obese women to have preeclampsia (adjusted relative risk [aRR], 1.7; 95% confidence interval [CI], 1.4 –2.1), macrosomia (aRR, 1.8; 95% CI, 1.3–2.5), and cesarean delivery (aRR, 1.8; 95% CI, 1.5–2.1). Almost one-half of all superobese women (49.1%) delivered by cesarean section, and 33.8% of superobese nulliparous women underwent scheduled primary cesarean delivery.
Women with a BMI of ≥50 kg/m2 are at significantly increased risk for perinatal complications compared with obese women with a lower BMI.
PMCID: PMC3516385  PMID: 22542116
pregnancy outcome; superobesity
21.  The Risk of Stillbirth and Infant Death Stratified by Gestational Age in Women with Gestational Diabetes 
To compare the different mortality risks between delivery and expectant management in women with gestational diabetes mellitus (GDM).
Study Design
This is a retrospective cohort study that included singleton pregnancies of women diagnosed with GDM delivering at 36-42 weeks gestational age (GA) in California from 1997-2006. A composite mortality rate was developed to estimate the risk of expectant management at each GA incorporating the stillbirth risk during the week of continuing pregnancy plus the infant mortality risk at the GA one week hence.
In women with GDM, the risk of expectant management is lower than the risk of delivery at 36 weeks, (17.4 vs. 19.3 per 10,000), but at 39 weeks, the risk of expectant management exceeds that of delivery (RR 1.8, 95% CI: 1.2 – 2.6).
In women with GDM, infant mortality rates at 39 weeks are lower than the overall mortality risk of expectant management for one week absolute risks of stillbirth and infant death are low.
PMCID: PMC3403365  PMID: 22464068
expectant management; gestational diabetes; infant mortality; stillbirth
22.  Perinatal morbidity associated with late preterm deliveries compared to deliveries between 37–40 weeks 
Bjog  2011;118(12):1446-1454.
To estimate the risk of short-term complications in neonates born between 34 and 36 weeks by week of gestation.
This is a retrospective cohort study.
Deliveries in 2005 in the United States of America.
Singleton live births between 34 and 40 weeks gestational age.
Gestational age was subgrouped into 34, 35, 36 and 37–40 completed weeks. Statistical comparisons were performed using chi-square test and multivariable logistic regression models, with 37–40 weeks gestational age designated as referent.
Main Outcome Measures
Perinatal morbidities, including 5-minute Apgar scores, hyaline membrane disease, neonatal sepsis/antibiotics use, and admission to the intensive care unit.
There were 175,112 neonates born between 34 and 36 weeks in 2005. Compared to neonates born between 37 and 40 weeks, neonates born at 34 weeks had higher odds of 5-minute Apgar<7 (adjusted odds ratio [aOR]=5.51, 95% CI [5.16–5.88]), hyaline membranes disease (aOR=10.2 [9.44–10.9]), mechanical ventilation use >6 hours (aOR=9.78 [8.99–10.6]) and antibiotics use (aOR=9.00 [8.43–9.60]). Neonates born at 35 weeks were similarly at risk of morbidity, with higher odds of 5-minute Apgar <7 (aOR 3.42 [3.23–3.63], surfactant use (aOR 3.74 [3.21–4.22], ventilation use >6 hours (aOR 5.53 [5.11–5.99] and NICU admission (aOR 11.3 [11.0–11.7). Further, neonates born at 36 weeks remain at higher risk of morbidity compared to deliveries at 37–40 weeks.
While the risk of undesirable neonatal outcomes decreases with increasing gestational age, the risk of neonatal complications in late preterm births remains higher compared to infants delivered at 37–40 weeks gestation.
PMCID: PMC3403292  PMID: 21883872
late preterm births; perinatal outcomes
23.  Treatment of gestational diabetes mellitus: glyburide compared to subcutaneous insulin therapy and associated perinatal outcomes 
To examine perinatal outcomes in women with gestational diabetes mellitus treated with glyburide compared to insulin injections.
Study design
This is a retrospective cohort study of women diagnosed with gestational diabetes mellitus (GDM) who required pharmaceutical therapy and were enrolled in the Sweet Success California Diabetes and Pregnancy Program between 2001 and 2004, a California state-wide program. Women managed with glyburide were compared to women treated with insulin injections. Perinatal outcomes were compared using chi-square test and multivariable logistic regression models; statistical significance was indicated by p < 0.05 and 95% confidence intervals (CI).
Among the 10,682 women with GDM who required medical therapy and met study criteria, 2073 (19.4%) received glyburide and 8609 (80.6%) received subcutaneous insulin injections. Compared to insulin therapy and controlling for confounders, oral hypoglycemic treatment was associated with increased risk of birthweight >4000 g (aOR = 1.29; 95% CI [1.03–1.64]), and admission to the intensive care nursery (aOR = 1.46 [1.07–2.00]).
Neonates born to women with gestational diabetes managed on glyburide, and were more likely to be macrosomic and to be admitted to the intensive care unit compared to those treated with insulin injections. These findings should be examined in a large, prospective trial.
PMCID: PMC3443974  PMID: 21631239
Gestational diabetes mellitus; treatment; perinatal outcomes
24.  Treating mild gestational diabetes mellitus: a cost-effectiveness analysis 
This study investigated the cost-effectiveness of treating mild gestational diabetes mellitus (GDM).
A decision analytic model was built to compare treating vs not treating mild GDM. The primary outcome was the incremental cost per quality-adjusted life year (QALY). All probabilities, costs, and benefits were derived from the literature. Base case, sensitivity analyses, and a Monte Carlo simulation were performed.
Treating mild GDM was more expensive, more effective, and cost-effective at $20,412 per QALY. Treatment remained cost-effective when the incremental cost to treat GDM was less than $3555 or if treatment met at least 49% of its reported efficacy at the baseline cost to treat of $1786.
Treating mild GDM is cost-effective in terms of improving maternal and neonatal outcomes including decreased rates of preeclampsia, cesarean sections, macrosomia, shoulder dystocia, permanent and transient brachial plexus injury, neonatal hypoglycemia, neonatal hyperbilirubinemia, and neonatal intensive care unit admissions.
PMCID: PMC3443977  PMID: 22071065
cost-effectiveness; decision analysis; gestational; diabetes mellitus
25.  Delivery After Prior Cesarean: Maternal Morbidity and Mortality 
Clinics in perinatology  2011;38(2):297-309.
PMCID: PMC3428794  PMID: 21645797
VBAC; Pregnancy; Pregnancy complications; Cesarean section; Evidence review

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