Women who have low levels of folic acid in their blood during early pregnancy are more likely to give birth to low-birthweight infants than women who have higher blood levels of the vitamin in early pregnancy, according to a study published recently in the British Journal of Nutrition, BBC News reports. Although consumption of folic acid -- also known as folate or vitamin B9 -- among pregnant women already is known to reduce the risk of neural tube defects, this is the first study to link folic acid deficiency to low birthweight (BBC News, 8/4). Caroline Relton of the Newcastle University School of Clinical Medical Sciences and colleagues studied 998 women who delivered at West Cumberland Hospital in Whitehaven, England, and their infants (Hawkes, Times, 8/5). The women underwent blood tests at approximately three months gestation and were questioned about their lifestyle, including smoking habits (Macrae, Daily Mail, 8/5). The researchers found that for each additional unit of folic acid present in a pregnant woman's blood, her infant's birthweight increased by 14% (Times, 8/5). Women who smoked were particularly likely to have lower levels of folic acid, possibly because the vitamin is stored in red blood cells and smoking might hamper the blood cells' ability to store folic acid (Daily Mail, 8/5). The findings have prompted calls for the vitamin to be included in foods such as flour and cereals in the United Kingdom, where 7% of infants are low birthweight -- defined as less than 5.5 pounds (Frith, Independent, 8/5).