Maternal HIV and the Risk of Low Birth Weight and Preterm Birth in Western Kenya: Evidence from a Prospective Cohort Using Propensity Score Methods

Abstract Despite widespread use of antiretroviral therapy (ART), maternal HIV infection remains a major public health concern in sub-Saharan Africa, and its association with adverse birth outcomes such as low birth weight (LBW) and preterm birth (PTB) inconsistently reported. This study investigates the association between maternal HIV infection and the risk of LBW and PTB in Western Kenya, comparing advanced statistical methods to control for confounding. We conducted a Kenya-specific sub-analysis of documented pregnancy outcomes (n = 2,399) from PRISMA Maternal and Newborn Health Study , a multi-country, prospective open-cohort study that enrolled pregnant participants before 20 weeks of gestation through community-hospital based surveillance. Weighted Propensity Score Matching (WPSM) and Inverse Probability Weighting (IPW) were employed to control for potential confounders—including job type, maternal age, parity, residence, wealth quantile, education level—and to compare effect estimate robustness. Log binomial generalized linear mixed effects models were used to assess the association. The median age was 26 years, and overall HIV prevalence was 13.0% (311/2,399), showing a strong age gradient—from 5.6% among participants < 20 years to 30.6% among those ≥ 35 years. All women living with HIV (WLWH) reported being on antiretroviral therapy during pregnancy. Using WPSM, WLWH were more likely to have infants with LBW [ Relative Risk (RR) = 1.68, 95% CI: 1.39–2.03] and PTB [ RR = 1.68 95% CI: 1.41–2.01]. IPW yielded similar results in direction, with slightly differing risk estimates for LBW [RR = 1.66, 95% CI: 1.51–1.82] and PTB [RR = 1.32, 95% CI: 1.21–1.44]. Maternal HIV infection, despite antiretroviral therapy, is independently associated with an increased risk of LBW and PTB. Consistency across two propensity score methods strengthens confidence in these findings. Strengthening integrated maternal HIV and antenatal care services is critical for reducing the residual burden of adverse birth outcomes among HIV-exposed pregnancies.