Mothers-to-be with lower levels of the vitamin folic acid in their body during early pregnancy are more likely to have babies with lower, or less healthy, birth weights, a study has revealed. Conversely, researchers, who examined nearly 1,000 women and their newborn babies, found that higher levels of folic acid (found in some vegetables, fruits and cereals) were linked with increased birth weights.

Expectant mothers who smoked were more likely to have lower levels of folic acid in their blood, which might explain why women who smoke often have lighter babies. About 7% of all babies born are low birth weight (less than 2.4kg or 5.5lbs) and they have a 50% chance of having a severely disabling condition as a result of being too light. Healthy birth weights are a marker for good health in infancy and later life.

The health benefits of folic acid for babies are already known but this is the first time that folic acid levels commonly seen in UK mothers in early pregnancy have been linked with birth weight.

Medical evidence suggests that folic acid influences birth weight because it is an essential nutrient for growth and gene expression in the fetus. Smoking is likely to reduce a woman’s folic acid levels because it is a significant source of oxidative stress and may alter the ability of the cell to metabolise and ultimately store the vitamin.

The best way to increase folic acid levels is by taking supplements but it is also advisable to eat folic acid-rich foods like green vegetables (broccoli, spinach), citrus fruits (oranges, grapefruits) or wholemeal products like bread or cereals.

University of Newcastle upon Tyne, Aug 4, 2005