Women who gain either more or less weight than recommended during pregnancy may be more likely to have an overweight child, a new study has found.
Researchers looked at health records of 4,145 women, and the medical records of their children between ages 2 and 5.
They found that among women who had a normal body mass index (BMI) before pregnancy, those who gained less than the recommended amount (of 25 to 35 pounds) were 63 percent more likely to have a child who became overweight or obese, compared with those who gained the recommended amount. [7 Ways Pregnant Women Affect Babies]
Similarly, women with a normal BMI before pregnancy who gained more weight than recommended were 80 percent more likely to have an overweight or obese child, according to the study published today (April 14) in the American Journal of Obstetrics and Gynecology.
"Gaining either too little or too much weight in pregnancy may permanently affect mechanisms that manage energy balance and metabolism in the offspring, such as appetite control and energy expenditure," said study researcher Sneha Sridhar, a public health researcher at Kaiser Permanente division of research in Oakland, Calif.
"This could potentially have long-term effects on the child's subsequent growth and weight," Sridhar said.
Previous studies have shown that gaining too much weight during pregnancy can increase the risk of gestational diabetes for the mother, as well as increase the risk of health problems for the child, such as childhood obesity. But other studies have also shown that gaining too little weight during pregnancy can lead to complications such as preterm birth and small infants.
In the study, the researchers also found that among all women who gained more than the recommended weight during pregnancy, 20.4 percent had children who were overweight or obese, compared with 19.5 percent of women who gained less than the recommended weight and 14.5 percent of women who gained weight within the guidelines.
Women in the study were members of Kaiser Permanente health care plans in Northern California, and were racially diverse. They had completed a health survey between 2007 and 2009 and subsequently had a baby, the researchers said.
As for the children, the researchers considered a child overweight or obese if he or she had a BMI greater than 85 percent of children in their age group, following the Centers for Disease Control and Prevention child growth standards.
Obesity is partly genetic, but the finding that even normal weight women were more likely to have overweight children if they gained too much or too little weight during pregnancy, suggests that weight conditions during pregnancy may affect the child independently of genetic factors, said Monique Hedderson, another researcher on the study.
In fact, the impact of inappropriate weight gain during pregnancy on child's weight appeared to be stronger among normal weight women than among those who were obese or underweight before pregnancy, the researchers said.
According to the Institute of Medicine, the amount of weight that women are recommended to gain during pregnancy depends on their BMI before pregnancy. Obese women who have a BMI of 30 or greater are recommended to gain between 11 and 20 pounds during pregnancy, and overweight women (with a BMI between 25 and 29) are recommended to gain 15 to 25 pounds. Underweight women (with a BMI less than 18.5) are recommended to gain 28 to 40 pounds.
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