Background: Low maternal 25(OH)D (vitamin D) values have been associated with higher mortality and impaired growth among HIV-exposed uninfected (HEU) infants of antiretroviral (ART)-naive women. These associations have not been studied among HEU infants of women receiving ART.

Methods: We performed a nested case-control study in the Botswana Mma Bana Study, a study providing ART to women during pregnancy and breastfeeding. Median maternal vitamin D values, and the proportion with maternal vitamin D insufficiency, were compared between women whose HEU infants experienced morbidity/mortality during 24 months of follow-up and women with nonhospitalized HEU infants. Growth faltering was assessed for never hospitalized infants attending the 24-month-of-life visit. Multivariate logistic regression models determined associations between maternal vitamin D insufficiency and infant morbidity/mortality and growth faltering.

Results: Delivery plasma was available and vitamin D levels assayable from 119 (86%) of 139 cases and 233 (84%) of 278 controls, and did not differ significantly between cases and controls [median: 36.7 ng/mL, interquartile range (IQR): 29.1-44.7 vs. 37.1 ng/mL, IQR: 30.0-47.2, P = 0.32]. Vitamin D insufficiency (<32 ng/mL) was recorded among 112 (31.8%) of 352 women at delivery and occurred most frequently among women delivering in winter. Multivariate logistic regression models adjusted for maternal HIV disease progression did not show associations between maternal vitamin D insufficiency at delivery and child morbidity/mortality, or 24-month-of-life growth faltering.

Conclusions: Vitamin D insufficiency was common among ART-treated pregnant women in Botswana, but was not associated with morbidity, mortality or growth impairment in their HIV-uninfected children.