Mothers' size, habits affect child's birth weight

Women who are heavier or taller than average or whose pregnancies last longer than usual appear to be more likely than other women to have an extra-heavy baby. Previous studies have shown that exercising moderately while pregnant can reduce the risk of having a large baby. Researchers at the Harvard Medical School studied over 24,000 pregnancies of women who did not have diabetes. Women who weighed more than 80 kilograms (about 176 pounds) before they conceived or had at least two prior pregnancies had nearly twice the risk of having a high-birth-weight infant than average-sized women or first-time mothers. In keeping with other studies, the investigators also found that women who carried their baby for more than 42 weeks were more than twice as likely to deliver a high birth weight infant than were those who delivered at or before full term. However, the mother's age, alcohol consumption and marital status were not important factors in determining her baby's size. Women who are planning to get pregnant should see their doctor before they start trying because they should to be in the best health they can prior to conception. They should be eating well, avoiding obesity and exercising even before they try to get pregnant. Other factors that seem to increase the odds of having a big baby include having had at least two previous pregnancies, and a male fetus. The more education a woman has, the more likely she may be to have a baby who weighs more. While women have long been advised not to gain too much weight during pregnancy, the new study confirms that it may make sense to slim down before becoming pregnant. Identifying risk factors for high birth-weight is important, because having an extremely heavy baby can cause breathing problems in the infant, as well as a difficult delivery and long-term incontinence for the mother. In addition, a number of studies have suggested that heavy newborns tend to become heavy adults. But, as the researchers point out, it is often difficult to predict a child's birth weight, even during the mother's third trimester of pregnancy.