Multivitamin use may lead to fewer premature and SGA babies

September 1, 2011

Women who take multivitamins regularly around the time they become pregnant may have a lower risk of premature labor and giving birth to small-for-gestational-age (SGA) babies, a study of 35,897 women in the Danish National Birth Cohort suggests.

Women who take multivitamins regularly around the time they become pregnant may have a lower risk of premature labor and giving birth to small-for-gestational-age (SGA) babies, a study of 35,897 women in the Danish National Birth Cohort suggests.

Researchers examined multivitamin use during a 12-week period from 4 weeks before a woman’s last period to 8 weeks postpartum. Women who reported taking multivitamins regularly before and after conception had a lower risk of preterm birth (16%) and labor compared with nonusers, but only if they had a prepregnancy body mass index (BMI) less than 25. Regular supplement users, regardless of BMI, were also less likely to have an SGA baby, especially if they took supplements after conception. The study was published online July 27 in the American Journal of Clinical Nutrition.

“It may be that multivitamin use around the time of conception could be a safe and simple strategy to improve pregnancy outcomes, similar to folate supplementation,” the researchers write. They caution, however, that “before such advice is given, studies are needed to evaluate possible risks of early and late fetal deaths associated with periconceptional multivitamin use as well as other outcomes in the life course of the child.” 

The associations between multivitamin use and lower risk of preterm birth (in women who were not overweight) and SGA babies remained after adjusting for differences between users and nonusers, such as diet and smoking. The researchers note, however, that multivitamin use correlated strongly with lifestyle variables, and although the study accounted for many of these variables, it couldn’t “rule out the possibility of unmeasured confounding.”

The reasons overweight women didn’t show a lower risk of preterm birth with multivitamin use aren’t clear. Researchers speculate that higher nutrient requirements, metabolic dysregulation, or impaired absorption of nutrients in overweight women may be factors.

Read other articles in this issue of Special Delivery.