Maternal weight and birth outcomes among women on antiretroviral treatment from conception in a birth surveillance study in Botswana

Introduction Antiretrovirals such as dolutegravir (DTG) and tenofovir alafenamide (TAF) have been associated with excessive weight gain. The objective of this study was to understand the potential impact of ART-associated weight gain on pregnancy outcomes among women living with HIV. Methods Using data from the Tsepamo birth outcomes surveillance study in Botswana, we evaluated the relationship between maternal weight (and weight gain) and severe birth outcomes (very preterm delivery <32 weeks, very small for gestational age (SGA) <3rd percentile, perinatal death), macrosomia (birthweight > 4000 g) and maternal hypertension. We estimated the relative risk of each outcome by baseline weight (first weight in pregnancy <24 weeks) and second trimester average weekly weight gain (kg/week from 12 +/- 2 to 24 +/- 2 weeks) using log binomial regression and evaluated effect modification by ART regimen (DTG vs. Efavirenz (EFV)). Results Of 22,828 women on ART at conception with singleton deliveries between August 2014 and April 2020, 16,300 (71.4%) had a weight measured <24 weeks' gestation (baseline weight) and 4437 (19.2%) had weight measured both at 12 (+/- 2) weeks and 24 (+/- 2) weeks, allowing second trimester weight gain calculation. Compared to women with baseline weight 60 to 70 kg, low baseline weight (<50 kg) was associated with increased risk of very preterm delivery (aRR 1.30, 95% CI 1.03, 1.65) and very SGA (aRR1.96, 95% CI 1.69, 2.28). High baseline weight (>90 kg) was associated with increased risk of macrosomia (aRR 3.24, 95% CI 2.36, 4.44) and maternal hypertension (aRR 1.79, 95% CI 1.62, 1.97). Baseline weight was not associated with stillbirth or early neonatal death. For all outcomes, second trimester weight gain showed weaker associations than did baseline weight. Duration of pre-pregnancy ART (years) was associated with higher baseline weight for DTG but not for EFV, and the risk of maternal hypertension by baseline weight category was higher for DTG than EFV for all strata. Conclusions ART regimens associated with weight gain may reduce the number of women at risk for certain severe adverse pregnancy outcomes associated with low weight but increase the number at risk of macrosomia and maternal hypertension. Further research could determine whether weight-based ART treatment strategies improve maternal and child health.