Antiretrovirals such as dolutegravir (DTG) and tenofovir alafenamide (TAF) have been associated with excessive weight gain, but the impact of weight and weight gain on pregnancy outcomes is poorly described among women on antiretroviral treatment (ART).
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 <32weeks, very small for gestational age <3rd percentile, perinatal death), macrosomia (birthweight >4000g) 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]).
Of 22,828 women on ART at conception with singleton deliveries between August 2014-April 2020, 16,300 (71.4%) had a documented weight measured at <24 weeks gestation (baseline weight) and 4437 (19.2%) had documented weight measured both at 12 (+/-2) weeks and 24 (+/-2) weeks, allowing gestational weight gain calculation. Compared to women with baseline weight 60-70kg, low baseline weight (<50kg) was associated with increased risk of very preterm delivery (aRR 1.30, 95% CI 1.03,1.65) and very small for gestational age (aRR 1.96, 95% CI 1.69,2.28). High baseline weight (>90kg) 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)(Figure 1). Baseline weight was not associated with perinatal death. For all outcomes, gestational weight gain showed weaker associations than did baseline weight. Duration of pre-pregnancy ART (years) was associated with higher baseline pregnancy 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.
ART regimens associated with weight gain may reduce the percentage of low weight women at risk for certain severe adverse pregnancy outcomes but increase the number at risk of maternal hypertension. Further research is needed to determine whether weight-based ART treatment strategies could improve maternal and child health.