High infant birth weights seen in Latinos

Michelle Rizzo:

The weight of the mother before pregnancy, as well as additional weight gained during pregnancy, are often excessive and blood sugar abnormalities are common, in women of Mexican descent who are living in the U.S., researchers report. These factors help explain the high infant birth weights seen in this group, according to the study findings published in American Journal of Public Health.

"Despite the substantial proportion of Latino mothers who live in poverty and receive inadequate prenatal care, low birth weight is a rare outcome, especially among infants of Mexican ancestry," Dr. Edith C. Kieffer, of the University of Michigan, Ann Arbor, and colleagues note. However, this may be achieved at the expense of the mothers' health.

Although "many Latino infants are born healthy, this study helps demonstrate that many Latino infants' birth weights are higher because of less positive factors, namely their mothers' abnormally high blood sugar levels, prepregnancy overweight and obesity and excessive pregnancy weight gain," Kieffer commented to Reuters Health.

Kieffer's team examined the influence of maternal weight and other variables on infant birth weights among 1,041 Latino mother-infant pairs. The average age of the women was 25 years. Prenatal care was begun after an average of 17.4 weeks of pregnancy and the women had an average of 9.5 office visits.

Overall, 42 percent of women were overweight or obese before they became pregnant. The average weight gain during pregnancy was 28.4 pounds, and 36 percent of the women exceeded weight-gain recommendations.

At least some degree of blood sugar abnormalities was observed in 27 percent of the women and 6.8 percent had pregnancy-related, also called gestational, diabetes.

The average birth weight of the infants was 7.5 pounds. Thirteen percent of the infants born to women with gestational diabetes weighed 8.8 pounds or more, while only 8.8 percent of women without diabetes had infants this heavy, the researchers report.

After factoring in the duration of the pregnancy, the researchers found that previous weight, weight gain and blood sugar levels were predictors of high infant birth weights.

"Public health promotion programs, and health care policies and research have long made the assumption that babies who are not born (with a) low birth weight are healthy," Kieffer explained to Reuters Health. Even infants with abnormally high birth weights are often classified as "normal," without considering if their weights were influenced by the mother's obesity or abnormal blood sugar level, she said.

Evidence from other studies has shown that these potentially modifiable factors also increase the risk that mothers and their babies will develop diabetes, Kieffer noted.

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