Women who are pregnant may be able to reduce their newborn’s risk of Down’s syndrome by taking folic acid before pregnancy, according to researchers.

Folic acid, found in supplements and foods such as broccoli, protects against neural-tube defects, and researchers have found that families with a high-risk of such defects may also be at an increased risk of Down’s syndrome, or vice versa.

There may be a link between the two conditions, so researchers suggest a dose of five mg of folic acid could reduce the risk of Down's syndrome as well the risk of neural-tube defects (NTD) in newborns.

NTDs, which are the abnormal development of the neural tube, which becomes the brain or spinal cord, in early pregnancy, can cause serious mental and physical impairment. Spina bifida and anencephaly, the partial or complete absence of the brain, are the most severe NTDs.

Mothers of babies with NTDs have been found to have problems metabolizing folic acid, which may also be a risk factor for trisomy 21, the chromosomal abnormality that causes Down’s syndrome.

In a study of 493 families who had had a previous pregnancy which was affected by NTD and 516 families who had had a pregnancy affected by Down's syndrome, there were five times the number of Down’s syndrome affected pregnancies among the NTD group as expected from women of the same age.

Further, there was an increase in NTD cases in the families at a higher risk of Down's syndrome.

Researchers recommend that women take extra folic acid before conception and in the first two months of pregnancy, saying that folate supplementation during this time has the potential to reduce the risk of Down's syndrome.

Lancet April 19, 2003;361:1331-35