According to research published in the New England Journal of Medicine, in a randomized, placebo controlled trial, researchers provided 8468 pregnant women in Tanzania (negative for human immunodeficiency virus infection) with daily multivitamins at multiples of the RDA or placebo. The researchers observed that supplementation reduced the incidence of low birth weight and small-for-gestational-age births, but did not effect prematurity or fetal death.

Reference: NEJM Volume 356:1423-1431