Maternal BMI Influences Infant Weight Gain Regardless of HIV Exposure

Maternal body mass index influences infant weight gain in the first year of life regardless of HIV exposure status, a new study in South Africa found.

The study, published in Paediatric and Perinatal Epidemiology, included two prospective cohort studies in Cape Town, South Africa, of women living with HIV (WLHIV) and HIV-negative pregnant women and infants between 2013 and 2015. It involved a subset of 861 mother-infant pairs, including 407 children unexposed to HIV (CUH) and 454 children exposed but uninfected with HIV (CEUH).

“For a long time, we've been concerned about undernutrition in women living with HIV and their children,” lead author Angela Bengtson, PhD, assistant professor of epidemiology at Brown University, told Contagion. “Our work highlights the growing issue of obesity among women, including women living with HIV, in pregnancy and its potential to adversely impact women's health and contribute to childhood obesity.”

Investigators assessed age-and-sex-adjusted BMI (BMIZ), weight-for-length (WLZ) and weight-for-age (WAZ) z-scores, based on World Health Organization child growth standards, at six weeks and every three months for the first year after birth.

Nearly 20% of infants were overweight or obese by 1 year of age, regardless of HIV exposure.

Investigators examined the relationship between maternal BMI at entry to antenatal care and infant weight measures through the first year. Positive associations were reported between increasing maternal BMI category and increasing infant BMIZ/WLZ scores.

“Historically we've been more concerned about low weight in pregnancy among women living with HIV and suboptimal growth among HIV exposed children,” Bengtson said. “These issues remain important, but the high levels of maternal obesity and overweight observed among children, regardless of HIV exposure in utero, were surprising and concerning in our study.”

Median gestational age at birth was 39 weeks, 10% of infants were born preterm, and CEUH were slightly more likely to have low birth weight or to be born preterm. CUH were slightly heavier at birth. Differences in infant overweight by HIV exposure status diminished by 12 months of age.

“In some settings, obesity among women living with HIV and children exposed to HIV is a growing issue,” Bengtson said. “Addressing this will require integrating HIV care with interventions and care to address obesity and obesity-related complications like hypertension and diabetes. Pregnancy and early childhood are important times to talk with your patients about the importance of maintaining a healthy weight.”

The study authors noted that obesity during pregnancy has increased by nearly 20% since 2004, affecting up to 50% of pregnant women in South Africa. They also noted that overweight among children also is rising. The percentage of children under 5 in Southern Africa estimated to be overweight was 13% in 2018, up from 9% in 1990.

Investigators also analyzed maternal viral load before initiation of antiretroviral therapy and breastfeeding intensity and duration.

Maternal viral load was not associated with significant differences in trajectories of infant BMIZ and WLZ scores.

Exclusive breastfeeding was more common among CEUH and affected trajectories somewhat more for CUEH. Still, CUH had slightly higher BMIZ and WLZ scores regardless of breastfeeding status.

“We need better interventions to address obesity related issues in resource limited settings,” Bengtson said. “Our team is currently investigating how HIV and ART use influences obesity-associated complications, like preeclampsia and gestational diabetes, in pregnancy and investigating how to develop interventions to support healthy gestational weight gain in pregnancy and postpartum weight loss.”