Pregnancy and the risk of HIV-1 acquisition among women in Uganda and Zimbabwe.

OBJECTIVE: Several studies have suggested that pregnancy is associated with an increased risk of HIV-1 acquisition. We used data from a large, prospective study of hormonal contraception and HIV-1 to evaluate the effect of pregnancy on the risk of HIV-1 acquisition.
DESIGN: A multicenter prospective cohort study.
METHODS: We examined 4439 women from family planning sites in Uganda and Zimbabwe contributing 31 369 follow-up visits during 1999-2004. Participants were aged 18-35 years, and had received pregnancy and HIV-1 testing quarterly for 15-24 months. Using proportional hazards modeling, we compared the time to HIV-1 acquisition among four groups: pregnant women, non-pregnant lactating (NP/L) women, and women neither pregnant nor lactating (NP/NL) who were either using or not using hormonal contraception.
RESULTS: A total of 211 participants became HIV-1 infected (2.7 per 100 woman-years; wy), including 13 pregnant women (1.6 per 100 wy), 33 NP/L women (2.7 per 100 wy), 126 NP/NL women using hormonal contraception (2.9 per 100 wy), and 39 NP/NL women not using hormonal contraception (2.7 per 100 wy). In multivariable analysis adjusting for site, age, living with partner, risky sexual behaviors, and incident vaginal, cervical and herpes simplex virus 2 infections, neither pregnant, NP/L, nor NP/NL women using hormonal contraception were at an increased risk of HIV-1 acquisition compared with NP/NL women not using hormonal contraception.
CONCLUSION: Neither pregnancy nor lactation placed women at increased risk of HIV-1 acquisition in this multisite, prospective study of African women. This information is important in planning interventions to reduce HIV-1 acquisition among women.