Large Pregnancy Weight Gain Linked to Heavier Newborns
Within-family comparison shows this effect is independent of genetic factors
THURSDAY, Aug. 5 (HealthDay News) -- Women who put on excessive weight during pregnancy are more likely to give birth to heavier babies regardless of genetic factors, according to research published online Aug. 5 in The Lancet.
David S. Ludwig, M.D., of Children's Hospital in Boston, and Janet Currie, Ph.D., of Columbia University in New York City, used Michigan and New Jersey birth registry data for 1989 to 2003 to analyze multiple single pregnancies in the same mother (to exclude genetic confounders) for 513,501 women and their 1,164,750 offspring. Excluding cases of less than 37 weeks or more than 40 weeks gestation, maternal diabetes, and extreme birth weights (less than 500 g or more than 7,000 g), the researchers examined how differences in maternal weight gain in two or more pregnancies predicted the birth weights of the offspring.
The researchers observed a consistent association between maternal weight gain in pregnancy and birth weight. Infants of women who gained more than 24 kg during pregnancy were a mean 148.9 g heavier at birth than infants of women who gained just 8 to 10 kg. For the women who gained more than 24 kg during pregnancy, the risk of giving birth to an infant weighing more than 4,000 g was more than doubled (odds ratio, 2.26) compared to women who gained 8 to 10 kg.
"Maternal weight gain during pregnancy increases birth weight independently of genetic factors. In view of the apparent association between birth weight and adult weight, obesity prevention efforts targeted at women during pregnancy might be beneficial for offspring," the authors write.