B12 during pregnancy - can supplementation improve maternal and infant health?

A new study led by Drs Rubhana Raqib and Towfida Siddiqua from icddr,b’s Centre for Vaccine Sciences shows that vitamin B12 supplementation during pregnancy and lactation can help improve B12 levels in both mothers and infants, which is known to reduce the risk of birth defects and protects the health of mother and baby. Moreover, supplementation produced improvements in maternal H1N1 vaccine-specific response. The findings also shed important light on the dosage of supplement that can adequately address B12 deficiency.

The body’s requirement for B12 increases during pregnancy and lactation, and deficiency during this time has serious effects on the health of both mothers and infants: increasing risk of birth defects and exacerbating pregnancy complications such as preterm delivery, defective development of the spinal cord and brain and low birth-weight. Women in developing countries are particularly vulnerable due to risk factors such as limited intake of food from animal sources, malabsorption of nutrients and diarrhoeal infections.

In spite of the high global prevalence of B12 deficiency among pregnant women, few clinical studies have been conducted on B12 supplementation and its impact during pregnancy and postpartum development. The study by Dr Raqib and colleagues adds valuable evidence in this area.


The blinded, placebo-controlled trial took place in an urban hospital in Bangladesh between June 2010 and August 2012. Sixty-eight women between the ages of 18 and 35 and between 11-14 weeks of pregnancy were enrolled. The participants were randomised to receive 250 micro grams (one billionth of a gram) per day of B12 or a placebo, along with 60 milligrams of iron and 400 micro grams of folic acid throughout pregnancy and 3 months postpartum. The women were also immunised with an influenza vaccine at 26 to 28 weeks of gestation.

At the start of the trial 26% of the women were B12 deficient and 40% had a marginal level of B12. It was found that supplementation significantly increased the level of B12 in the blood, colostrum (first secretion from the breast after giving birth) and breast milk. Supplementation also increased the level of B12 in newborns and infants at 3 months. In fact, the level of B12 observed in infants after B12 supplementation were comparable to the level of B12 found in a previous study among healthy Norwegian infants.

Remarkably, women who received B12 supplementation demonstrated a significant improvement in their response to the influenza vaccine. However, no improvement in immunity was observed among the infants.

The study also adds to the evidence base on proper dosage and duration of B12 supplementation during pregnancy. While a 250 micro gram per day dosage in this study was found to be effective, a previous study in India showed that a dosage of 50 micrograms per day throughout pregnancy and 6 weeks postpartum did not meaningfully improve the B12 status among mothers or infants. Dr Raqib and colleagues recommend further research to help determine the optimal dosage and duration of B12 supplementation during pregnancy.

This study was funded by the Nestle Foundation, the Swedish International Development Cooperation Agency, the Bill & Melinda Gates Foundation and the intramural USDA-ARS Project. Incepta Pharmaceuticals Ltd donated the B12 and placebo pills. The first author, Dr Towfida Siddiqua, then a member of the Centre for Vaccine Sciences and now with icddr,b’s Centre for Nutrition and Food Security, received a Fogarty scholarship for PhD work in the Program in Community and International Nutrition at University of California Davis on the effects on anemia, biomarkers of vitamin B12 status, immune function and breast milk vitamin B12, which forms part of this paper.

Siddiqua TJ, Ahmad SM, Ahsan KB, Rashid M, Roy A, Rahman SM, Shahab-Ferdows S, Hampel D, Ahmed T, Allen LH, Raqib R. Vitamin B12 supplementation during pregnancy and postpartum improves B12 status of both mothers and infants but vaccine response in mothers only: a randomized clinical trial in Bangladesh. Eur J Nutr 2015 Feb 4.