BOSTON—Pregnant women who “eat for two" may cause their children to become obese adults regardless of heredity. A recent study published in The Lancet found maternal weight gain during pregnancy increases birthweight independently of genetic factors. A high birthweight is associated with adult obesity, so the researchers encouraged obesity prevention programs for moms-to-be.
The analysis of more than 513,000 women and their 1.1 million offspring showed a consistent association between pregnancy weight gain and birthweight. Infants of women who gained more than 53 pounds (24 kg) during pregnancy were 0.3 pounds heavier at birth than were infants of women who gained 22 pounds. The odds ratio of giving birth to an infant weighing more than 8.8 pounds (4,000 g) was more than twice as likely for women who gained more than 53 pounds during pregnancy compared with women who gained 22 pounds.
The study compared several pregnancies in the same mother using state-based birth registry data. Researchers David S Ludwig, M.D., from the Department of Medicine, Children's Hospital, Boston, and professor Janet Currie, Ph.D., from the Department of Economics, Columbia University, New York, noted this would help them control for genetic confounders.
The population-based cohort study used vital statistics natality records to examine all known births in Michigan and New Jersey between Jan. 1, 1989 and Dec. 31, 2003. They included women with more than one singleton birth, but excluded women who had:a gestation period less than 37 weeks or 41 weeks or more, maternal diabetes, birthweight less than 500 g or more than 7,000 g, and missing data for pregnancy weight gain. They examined how differences in weight gain that occurred during two or more pregnancies for each woman predicted the birthweight of her offspring.