Elsevier

The Lancet

Volume 338, Issue 8760, 20 July 1991, Pages 131-137
The Lancet

ORIGINAL ARTICLES
Prevention of neural tube defects: Results of the Medical Research Council Vitamin Study

https://doi.org/10.1016/0140-6736(91)90133-AGet rights and content

Abstract

A randomised double-blind prevention trial with a factorial design was conducted at 33 centres in seven countries to determine whether supplementation with folic acid (one of the vitamins in the B group) or a mixture of seven other vitamins (A, D, B1, B2, B6, C, and nicotinamide) around the time of conception can prevent neural tube defects (anencephaly, spina bifida, encephalocele). A total of 1817 women at high risk of having a pregnancy with a neural tube defect, because of a previous affected pregnancy, were allocated at random to one of four groups— namely, folic acid, other vitamins, both, or neither. 1195 had a completed pregnancy in which the fetus or infant was known to have or not have a neural tube defect; 27 of these had a known neural tube defect, 6 in the folic acid groups and 21 in the two other groups, a 72% protective effect (relative risk 0·28, 95% confidence interval 0·12-0·71). The other vitamins showed no significant protective effect (relative risk 0·80, 95% Cl 0·32-1·72). There was no demonstrable harm from the folic acid supplementation, though the ability of the study to detect rare or slight adverse effects was limited. Folic acid supplementation starting before pregnancy can now be firmly recommended for all women who have had an affected pregnancy, and public health measures should be taken to ensure that the diet of all women who may bear children contains an adequate amount of folic acid.

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  • Cited by (0)

    1

    This report was prepared by Nicholas Wald, with assistance from Joan Sneddon, James Densem, Christopher Frost, and Rossana Stone. For membership of steering committee, data monitoring committee, trial office staff, and representation of participating centres, see end of paper. Correspondence to Prof Nicholas Wald, Department of Environmental and Preventive Medicine, Medical College of St Bartholomew's Hospital, Charterhouse Square, London EC1 M 6BQ, UK

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