Mothers' multivitamin use before pregnancy associated with fewer preterm births

A study published in the November 2004 issue of the American Journal of Epidemiology found that the use of multivitamin supplements by women prior to becoming pregnant was associated with fewer preterm deliveries. Preterm birth is defined as birth at less than 37 weeks of gestation and is associated with a lower rate of infant survival during the first year of life.

Researchers at the University of North Carolina at Chapel Hill utilized data from the Pregnancy, Infection and Nutrition Study which recruited 2,010 women during their 24th to 29th week of pregnancy. Telephone interviews and food frequency questionnaires provided information on vitamin supplement use. The current study compared the incidence of preterm delivery among women who took multivitamins prior to conception, before conception and during pregnancy, during pregnancy only, or not at all.

The team found that women who took a multivitamin supplement before conception had half the risk of early and late preterm delivery than those who took no vitamins. Women used multivitamins before and during pregnancy or during pregnancy only had approximately the same amount of preterm births than women who took none at all.

The authors note that the women who took vitamins prior to conception, but discontinued taking them during pregnancy may have done so because of nausea, and that nausea and vomiting during early pregnancy has been associated with a lower risk of preterm delivery. A lower intake of nutrients during these months may modify the mother's hormones in a manner that benefits her offspring, possibly explaining the lack of benefit for multivitamins in women who took them both before and after conception. This study reinforces the concern that waiting until pregnancy is diagnosed may be too late for nutritional intervention to benefit pregnancy outcomes.

Source

American Journal of Epidemiology 11/2004; (volume 160, number 9)

Key concepts: multivitamin, pregnancy, preterm birth