Infants born to pregnant women living with HIV (WLHIV) are at greater risk for morbidity and mortality and may also have poorer developmental outcomes as compared with infants who are not exposed to HIV. Nutrition interventions in pregnancy may affect developmental outcomes.

This study evaluated the effect of maternal vitamin D supplementation on infant development outcomes.

We conducted a secondary analysis of a randomised, triple-blind, placebo-controlled trial of maternal vitamin D supplementation from June 2015 to October 2019.

Antenatal care clinics in Dar es Salaam, Tanzania.

Pregnant WLHIV and their offspring.

Daily 3000 IU vitamin D₃ or placebo supplements taken during pregnancy and lactation.

Infants were assessed for cognitive, language and motor development at 1 year of age with the Caregiver Reported Early Development Instruments (CREDI).

A total of 2167 infants were eligible, and 1312 of them completed CREDI assessments at 1 year of age. Vitamin D supplementation had no effect on overall CREDI z-scores (standardised mean difference (SMD) 0.03, 95% CI –0.09, 0.15, p value 0.66). There was also no evidence of a difference between vitamin D and placebo groups in language (SMD 0.06, 95% CI –0.08, 0.21, p value 0.40), motor (SMD 0.02, 95% CI –0.09, 0.14, p value 0.69) or cognitive domain z-scores (SMD 0.05, 95% CI –0.08, 0.17, p 0.48).

Maternal vitamin D supplementation during pregnancy and lactation did not affect infant development outcomes.

ClinicalTrials.gov identifier: NCT02305927.