Objective

To determine the risk and cofactors for HIV acquisition during pregnancy and postpartum.

Design

Prospective cohort study

Methods

Pregnant women in western Kenya were enrolled if HIV seronegative at that visit or within 3 months. Serial HIV nucleic acid amplification tests (NAATs) were conducted at 1–3 month intervals to 9 months postpartum. Genital swabs were collected for detection of chlamydia and gonorrhea at baseline, and for trichomonas, bacterial vaginosis (BV), and yeast at baseline and follow-up.

Results

Among 1304 pregnant women, median age was 22 years, 78% were married for a median of 4 years, 66% reported knowing partner HIV status, and 8% reported using condoms. Study retention was 98%. During 1235 person-years of follow-up, HIV incidence was 2.31/100 person-years (95% Confidence Interval [CI]:0.71–4.10). Incident HIV was associated with syphilis (Hazard Ratio [HR] 9.18, 95% CI:2.15–39.3), chlamydia (HR 4.49, 95% CI:1.34–15.0), BV (HR 2.91, 95% CI:1.25–6.76), yeast (HR 3.46, 95% CI:1.46–8.19), STI history (HR 3.48, 95%, CI:1.31–9.27), lifetime number of sex partners, (HR 1.19, 95% CI:1.03–1.37), partner age discordance (HR 1.07 per year, 95% CI:1.02–1.13) and shorter marriage (HR 1.19 per year, 95% CI:1.03–1.38). No women with incident HIV reported an HIV-infected partner. In multivariate analyses, chlamydia, older partners, and yeast infection remained significant; however, power was limited.

Conclusions

Pregnant and lactating women may not perceive HIV risk and rarely used condoms. Prevention and treatment of genital infections and risk stratification to identify women for pre-exposure prophylaxis (PrEP) could decrease HIV acquisition in pregnant/lactating women.