A total of 1,412 women (contributing 9,039 person-years) were at risk for becoming pregnant between 2002–2009. Of those, 941 (67%) were HIV-infected and 471 (33%) were HIV-uninfected. Over study follow-up, 456 unique women reported 766 pregnancies.
Demographic characteristics were reported at first visit between 2002–2009 (baseline visit) stratified by HIV status. HIV-infected women were older, with a median age of 34 years (inter-quartile range, IQR, 29–39), than HIV-uninfected women (median 30 years, IQR 23–37; p <0.001). HIV-infected women were more likely than HIV-uninfected women to report being married or living with a partner (38% vs. 25%, respectively); of those never married, 41% were HIV-infected and 52% HIV-uninfected (p<0.001). Two percent of HIV-infected women and 8% of HIV-uninfected women reported exchanging sex since their last visit (p<0.001). Use of any contraceptives in the past 6 months was reported by 84% of HIV-infected and 79% of uninfected women (p<0.018).
The number of male sex partners reported in the past 6 months was statistically different by HIV status (p<0.001). 8% of HIV-infected women and 6% of HIV-uninfected women reported having zero male sex partners; eligibility required at least 1 male partner within the last year. Among HIV-infected women, 80% reported having one male partner in the past 6 months, compared to 53% of HIV-uninfected women, while 12% of HIV-infected women and 41% of uninfected women reported ≥2 male partners.
Parity among HIV-infected women was statistically different from HIV-uninfected women (p<0.001). Twenty-three percent of HIV-infected women reported having zero prior births (alive or still born) compared to 35% of HIV-uninfected women. Forty-seven percent of HIV-infected and 41% of HIV-uninfected women had 1 or 2 prior births. Twenty-four percent of HIV-infected women reported greater than 3 prior births compared to 30% reported among HIV-uninfected women.
Among HIV-infected women the median viral load at baseline was 540 copies/ml (IQR 80–99,000 cp/ml), and median CD4+ lymphocyte count was 497 cells/μL (IQR 298–655). There were 619 (66%) HIV-infected women on antiretroviral therapy and 321 (34%) women not on therapy.
Of the 766 reported pregnancies, 404 (53%) were among HIV-infected women and 362 (47%) among HIV-uninfected women. Additionally, 192 pregnancies occurred at the same visit hormonal contraception was reported. The overall incidence rate of pregnancy was 1.2 per 100 person-years (95% C.I.: 1.1–1.3 per 100 person-years). The incidence rate of pregnancy among HIV-infected women was significantly lower [0.95 per 100 person-years (95% C.I.: 0.86–1.0 per 100 person-years)] than among HIV-uninfected women [1.7 per 100 person-years (95% C.I.: 1.5–1.9 per 100 person-years)].
shows the results of the Poisson regression and generalized gamma analyses, adjusted for age, parity, alcohol consumption, exchanging sex, number of male sex partners and contraception use in the past 6 months. HIV infection was associated with a 40% reduction in the incidence rate of pregnancy (Incidence Rate Ratio, IRR=0.60, 95% C.I.: 0.46–0.78). The time for HIV-infected women to become pregnant was 73% longer relative to HIV-uninfected women (Relative Time, RT=1.73 95% C.I.: 1.35–2.36).
Incidence rate ratio and Relative Time to First Pregnancy between 2002–2009*
Older age was also associated with a reduction in the incidence rate of pregnancy and longer time to first pregnancy (IRR=0.89, 95% C.I.: 0.88–0.91). The relative time to pregnancy was 30% longer (RT=1.3, 95% C.I.: 1.12–1.70).
Women with ≥2 sex partners in the past 6 months had a 28% lower pregnancy rate (IRR=0.72, 95% C.I.: 0.53–0.94) and 64% longer time to pregnancy (RT=1.64, 95% C.I.: 1.12–2.40) as compared to women with ≤1 sex partner.
Women with parity ≥3 births conceived the fastest, with relative time to conception 0.14 (95% C.I.: 0.09–0.21) compared to women with no prior births. The relationship between parity and pregnancy was similar when examining incidence rate ratios. Compared to nulliparous women, women with ≥3 prior births had an incidence rate of pregnancy that was more than 12 times higher (IRR=12.64, 95% C.I.: 8.33–19.15).
shows the Kaplan-Meier plot of time to first pregnancy by CD4+ count among HIV-infected women. Women with CD4+ counts ≥350 cells/μl experienced statistically significant faster times to pregnancy compared to women with CD4+ counts <350 cells/μl (log rank p< 0.0073).
Time to First Pregnancy for HIV Infected women, 2002 to 2009