The use of vitamin supplements by women around the time of conception was examined and compared in those having babies with neural tube defects, those with still births or some other type of malformation, and in women who had normal babies. The study was performed at the National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Northwestern University, Chicago; and the California Public Health Foundation, Berkley. The rate of periconceptional multivitamin use among mothers of infants with neural tube defects (15.8%) was not significantly different from the rate among mothers in either the abnormal or the normal control group (14.1% and 15.9%, respectively). There were no differences among the groups in the use of folate vitamin supplements. The authors conclude that the periconceptional use of multivitamins or folate-containing supplements did not decrease the risk of having an infant with a neural tube defect. [1]

COMMENT. Several studies have suggested that women who take multivitamins or supplements of folic acid around the time of conception may have a reduced risk of delivering an infant with a neural tube defect such as myelomeningocele or spina bifida. British studies have reported that folic acid in a dose of 4 mg/day or multivitamins can reduce the risk of recurrence in women who have already delivered an infant with such a defect. In a report published from the Atlanta Birth Defects Case Control Study, mothers of children with neural tube defects were significantly less likely to report vitamin use around the time of conception than were the mothers of infants with other malformations or normal control children. The results of the present study were strikingly different from those of the Atlanta Birth Defects Case Control Study in which 7% of mothers with affected babies and 50% of controls reported using multivitamin supplements at least three times a week in the periconceptional period. It is possible that the use of vitamins was not itself protective but was a marker for other health conscious behavior that prevented the malformations. Other explanations for the difference in the results might include the variation in the years studied and geographic differences. It should be noted that the Vitamin A analog Isotretinoin is teratogenic and should be avoided during pregnancy. Further studies are obviously needed to confirm these results. In the meantime mothers might be advised to take vitamins in the recommended daily allowances but not to resort to megavitamin therapy with possible adverse effects.