Vitamin D supplementation has many benefits. It helps regulate the amount of calcium and phosphate in the body, thereby keeping bones, teeth, and muscles healthy. However, it is not clear how maternal vitamin D supplementation during pregnancy and lactation impacts fetal and infant growth. This study aims to evaluate the effects of maternal vitamin D supplementation during pregnancy and breastfeeding on fetal and infant growth.

This is a randomized, double-blind, placebo-controlled trial conducted on a total of 1,164 infants with prenatal vitamin D supplementation and postpartum vitamin D supplementation. A control (placebo) group was also included that received neither prenatal nor postpartum vitamin D. The primary outcome of the study was the improvements in fetal or infant growth.

Out of 1,164 infants examined at the age of 1 year, no significant differences across groups were found. Anthropometric measures, like birth outcomes and morbidity, were also comparable across the groups. There was no significant difference in the occurrence of adverse events across the three groups.

The research concluded that in population with widespread vitamin D deficiency and fetal and infant growth restriction, maternal supplementation of vitamin D during pregnancy or lactation was not associated with improved fetal or infant growth.