Vitamin B12 in pregnancy and health outcomes
What it found
In five trials with 984 pregnant women, vitamin B12 supplements raised vitamin B12 levels in mothers and babies.
The evidence on other health outcomes is very uncertain.
What they found
Studies in people
Maternal anaemia
There may be little to no difference in anaemia between women who took vitamin B12 and those who did not, but the evidence is very uncertain. Anaemia was found in 70.9% of supplemented women and 65.0% of unsupplemented women.
Maternal B12 deficiency
Vitamin B12 supplements during pregnancy may reduce the risk of maternal vitamin B12 deficiency compared to placebo or no supplement, but the evidence is very uncertain. Deficiency was found in 25.9% of supplemented women and 67.9% of unsupplemented women.
Maternal B12 levels
Women who took vitamin B12 supplements during pregnancy may have higher total vitamin B12 concentrations than those who did not. The average difference was 60.89 pmol/L, but the results varied substantially between trials.
Pregnancy outcomes
The evidence is uncertain about the effect on preterm birth and low birthweight. Two trials reported miscarriage data but did not provide numbers that could be combined, and no trials looked at neural tube defects.
Infant B12 levels
Children born to women who took vitamin B12 supplements had higher total vitamin B12 concentrations than those born to women who did not. The average difference was 71.89 pmol/L.
Child development
In one study, maternal vitamin B12 supplementation did not improve neurodevelopment at 9 months or neurophysiological outcomes at 72 months compared to placebo. However, children born to supplemented women had improved expressive language at 30 months.
What the authors conclude
“Oral vitamin B 12 supplementation during pregnancy may reduce the risk of maternal vitamin B 12 deficiency and may improve maternal vitamin B 12 concentrations during pregnancy or postpartum compared to placebo or no vitamin B 12 supplementation, but the evidence is very uncertain.”
Also in their conclusions
- They conclude that oral vitamin B12 supplementation during pregnancy may reduce the risk of maternal vitamin B12 deficiency and may improve maternal vitamin B12 concentrations during pregnancy or postpartum compared to placebo or no vitamin B12 supplementation, but the evidence is very uncertain.
- They state that the effects on other primary outcomes were not reported, or were not reported in a format for inclusion in quantitative analyses.
- They advise that vitamin B12 supplementation during pregnancy may improve maternal and infant vitamin B12 status, but the potential impact on longer-term clinical and functional maternal and child health outcomes has not yet been established.
How it was done
Vitamin B12 deficiency is a major public health problem worldwide, with the highest burden in elderly people, pregnant women, and young children. Because of its role in DNA synthesis and methylation, folate metabolism, and red blood cell production, supplementing during pregnancy may give longer-term benefits to mother and child.
They looked at five randomised trials with 984 pregnant women in low- and middle-income countries, including India, Bangladesh, South Africa, and Croatia. The women took 5 to 250 micrograms of vitamin B12 a day, starting at 8 to 28 weeks of pregnancy and continuing until delivery or three months after birth. Three trials with 609 women provided data for combining results.
What it can’t tell you
- We summarised it from the abstract only.
- The evidence is very uncertain, so it is not clear whether vitamin B12 supplements during pregnancy improve outcomes like anaemia, preterm birth, or low birthweight.
- The trials did not look at neural tube defects, and data on miscarriage could not be combined.
- The long-term effects on mother and child health are not known.
Who paid
- Funding
- Funded by NICHD NIH HHS; NCBDD CDC HHS (from the PubMed record).
- Conflicts
- The protocol for this review was initially developed during the World Health Organization (WHO)/Cochrane/Cornell University Summer Institute for Systematic Reviews in Nutrition for Global Policy Making, held annually at the Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA (Finkelstein 2020). The WHO has partially supported this programme beginning in 2014. The protocol was not directly supported by the WHO. JLF is a principal investigator on research grants to examine the burden and aetiology of anaemia in women of reproductive age (US Centers for Disease Control and Prevention), biomarkers of anaemia and nutritional status in women of reproductive age (National Institutes of Health), and to conduct randomised trials with micronutrient interventions to improve the health of women of reproductive age (US Centers for Disease Control and Prevention). JLF has no known conflicts of interest to declare. AF is an employee of the US Government at the Centers for Disease Control and Prevention and has no known conflicts of interest to declare. SV has no known conflicts of interest to declare. YPQ is an employee of the US Government at the Centers for Disease Control and Prevention and has no known conflicts of interest to declare. AJL has no known conflicts of interest to declare. JLW is an employee of the US Government at the Centers for Disease Control and Prevention working as a PhD nurse epidemiologist and family nurse practitioner for the US Public Health Service and has no known conflicts of interest to declare. KSC is an employee of the US Government at the Centers for Disease Control and Prevention and has no known conflicts of interest to declare. None of the authors are investigators on any trials included in this review.
- Authors work at
- Cornell University, USA; National Center on Birth Defects and Developmental Disabilities, USA; University of Pittsburgh, USA
The paper
- Title
- Vitamin B12 supplementation during pregnancy for maternal and child health outcomes
- Type
- Systematic review
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Finkelstein JL, Fothergill A, Venkatramanan S, et al (2024). Vitamin B12 supplementation during pregnancy for maternal and child health outcomes. The Cochrane database of systematic reviews. doi:10.1002/14651858.CD013823.pub2Free full textPubMed 38189492DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error