Women may be able to halve the risk of giving birth prematurely by taking folic acid a year before becoming pregnant, a study published in the United States on Thursday said.
Women taking the supplements -- a form of vitamin B -- can reduce by 50 to 70 percent the risk of a premature birth, which can cause mental retardation, blindness or lung problems in a child, according to the study.
Trials run by the National Institutes of Health monitored 38,000 women between 1999 and 2002.
"Folate supplementation for at least one year is linked to a 70 percent decrease in very early preterm deliveries (20 to 28 weeks ... ) and up to a 50 percent reduction in early preterm deliveries of 28 to 32 weeks," said the study's leader author Radek Bukowski of the University of Texas, in a report.
Found in green vegetables, fruit and beans, folic acid aids the reproduction of cells.
Alan Fleischman of the non-profit pregnancy health foundation March For Dimes said the research bolstered US public health authorities' recommendation that all women of childbearing age take 400 micrograms of folic acid a day.
The research was presented at the annual meeting of gynecologists and obstetricians held by the Society for Maternal-Fetal Medicine in Dallas, Texas.