Vitamin D3 and B12 supplementation in pregnancy

To assess the efficacy of vitamin D3 or B12 supplementation during pregnancy.

Pregnant women at 6-14 weeks in the intervention arm received oral high dose intermittent vitamin D3 and/or low dose B12 supplementation if they had vitamin D or vitamin B12 deficiency. The control arm received prescribed dietary instruction only. An additional observational arm for those mothers at booking with normal vitamin D and vitamin B12 level was also recruited. All groups received standard care during pregnancy.

The primary endpoint of either vitamin D or B12 at term was not met. At baseline 25% participants in both the interventional and control arms had severe D deficiency (<30 nmol/l), reducing to under 3.4% in both groups. No maternal differences in vitamin D or B12 levels were found at delivery between the intervention, control, or observational groups. No significant difference in any of the pregnancy or birth outcomes was observed between three groups.

In this study, oral supplementation of high dose intermittent vitamin D or low dose vitamin B12 regime failed to correct the relevant nutritional deficiencies in Bangladeshi pregnant women as per protocol. Both dietary supplementation and high dose vitamin D corrected severe vitamin deficiency.