Pregnancy outcomes in women living with HIV and HIV-negative women in South Africa: Cohort analysis based on bias-corrected gestational age.

Background: Antiretroviral therapy (ART) use during pregnancy may be associated with adverse outcomes, but findings have been inconsistent, at least in part due to unreliably estimated gestational age.

Objective: To quantify the association between HIV status, ART initiation timing and adverse birth outcomes, with reliably assessed gestational age at booking, in a public sector primary care facility in Cape Town, South Africa.

Methods: Pregnant women, HIV-negative or living with HIV (WLHIV), were enrolled at first antenatal care visit and followed through delivery. Ultrasound-assessed gestational age was deemed the gold standard. Based on quantitative bias analysis for outcome misclassification, gestational age by non-ultrasound assessment was corrected using multiple overimputation, which deals with missing data and measurement error simultaneously. Using bias-corrected gestational age, birth outcomes were compared between WLHIV and HIV-negative women, and among WLHIV who initiated ART before versus during pregnancy, further divided into trimesters.

Results: Of 3952 women enrolled, 37% were WLHIV (mostly using tenofovir + emtricitabine + efavirenz). Last menstrual period (LMP)-based gestational age was identified to be biased, and LMP measures were thus corrected using multiple overimputation. Comparing WLHIV and HIV-negative women, adjusted risk ratio (aRR) of overall pregnancy loss was 1.26 (95% confidence interval [CI] 0.98, 1.61); aRR of preterm delivery was 1.02 (95% CI 0.88, 1.20); aRR of small for gestational age infants was 1.43 (95% CI 1.14, 1.80). Among WLHIV, outcomes were similar by ART initiation timing.

Conclusions: In this routine care cohort, risk of SGA, and possibly of pregnancy loss, was increased in WLHIV compared with HIV-negative women, with no evidence of increased risk of preterm delivery. Further research is needed to improve mechanistic understanding of the contribution of ART to adverse birth outcomes to optimize treatment for pregnant WLHIV and ensure optimal maternal and infant outcomes.