Maternal nutritional deficiencies are linked with poor pregnancy outcomes and vitamins are often advertised to pregnant women. But evidence for multivitamins mostly comes from studies of women in poor countries.
A report in the Drug and Therapeutics Bulletin (online, 11 July 2016)
reviewed the evidence behind official UK guidance, which recommends vitamin D and folic acid supplements but not multivitamins.
The authors found strong support for daily folic acid supplementation during early pregnancy to prevent neural tube defects. But the evidence was unclear for vitamin D supplementation, with little evidence from randomised controlled trials. The review also found no evidence from available data to support the use of multivitamin supplements.
The team concludes that the focus should be on improving access to folic acid and vitamin D supplements, but that multivitamins promoted to women in the UK are an unneeded expense.