Association between in utero zidovudine exposure and nondefect adverse birth outcomes: analysis of prospectively collected data from the Antiretroviral Pregnancy Registry

OBJECTIVE: To examine the association between nondefect adverse birth outcomes and in utero exposure to zidovudine (ZDV)‐containing regimens versus non‐ZDV antiretroviral (ARV) regimens. DESIGN: Analysis of prospectively‐collected data. SETTING: Global. POPULATION: HIV‐infected pregnant women prenatally exposed to antiretrovirals. METHODS: Estimation of prevalence of and risk for nondefect adverse birth outcomes among HIV‐infected women. MAIN OUTCOME MEASURES: Prevalence of and risk for nondefect adverse birth outcomes. RESULTS: Among 12 780 singleton birth outcomes with in utero ZDV exposure, 96.1% were live births; 3.9% were spontaneous abortions, induced abortions or stillbirths. Among live births, 16.4% were low birthweight (LBW); 12.3% were premature. Among 1904 outcomes with in utero exposure to non‐ZDV ARV regimens, 85.8% were live births; 14.2% were spontaneous abortions, induced abortions or stillbirths. Among live births, 14.1% were LBW; 12.4% were premature. Relative risk comparing exposure to ZDV‐containing ARV regimens to non‐ZDV ARV regimens for spontaneous abortions was 0.18 (95% confidence interval [95% CI] 0.14–0.22); induced abortions 0.28 (95% CI 0.22–0.36); stillbirths 0.76 (95% CI 0.51–1.12); premature births 1.00 (95% CI 0.87–1.15) and LBW 1.17 (95% CI 1.02–1.33). CONCLUSION: Prevalence of nondefect adverse birth outcomes is lower among outcomes with in utero ZDV exposure versus in utero non‐ZDV ARV exposure. The risks for spontaneous and induced abortions were no different for ZDV‐containing regimens versus non‐ZDV ARV regimens. For premature births and stillbirths, there was no significant difference in risk between the two regimens. The risk of LBW was statistically significantly higher among ZDV‐containing regimens versus non‐ZDV ARV regimens. TWEETABLE ABSTRACT: ZDV‐containing regimens do not increase the risk for nondefect adverse birth outcomes.