Women who gain too much weight during and after pregnancy could increase the risk that their child will be overweight or obese in adolescence, a new study from the Netherlands suggests.
The study researchers explained that a mother's excessive weight gain during pregnancy may be tied to changes in her chemistry that make the child more likely to be overweight or obese. The mother's weight gain after giving birth and the child's subsequent weight gain probably reflect the family's lifestyle and health behaviors, the study authors said.
One U.S. doctor noted the importance of both factors.
"There is widespread recognition that environments and so-called 'social determinants of health' have a major influence on weight gain and obesity," said Dr. David Katz, director of the Yale University Prevention Research Center in New Haven, Conn.
The first environment is the womb, and the first social influence is mothers' behaviors, he said. This study highlights the importance of these factors and reaffirms a relationship between excessive weight gain during pregnancy and the likelihood of obesity in the child, said Katz, who wasn't involved in the research.
Katz said the novelty of this study is the separation of the association of weight gain in pregnancy from maternal weight gain after pregnancy, which also is an obesity risk in children. "Essentially, we have evidence here that all environments are important, from the womb to the living room," he said.
However, the study only found an association and not a cause-and-effect relationship between a mom's pregnancy and post-pregnancy weight and her child's weight.
The study was published Oct. 19 in Pediatrics.
The research included information on more than 3,300 Dutch children and their mothers. Children born to mothers whose pregnancy weight gain was deemed "excessive" had 20 percent greater odds of being overweight. Likewise, kids whose mothers gained too much weight in the year following delivery also faced an increased risk of being overweight themselves, the study found.
And children born to moms who gained too much weight both during and after pregnancy had more than three times higher odds of ending up overweight at age 14 compared to kids with slimmer moms, the research revealed.
Katz thinks these findings can be used to educate women before and during pregnancy about the importance of lifestyle, emphasizing healthy eating, healthy activity and weight management.
"Pregnancy is a teachable moment, and using it can benefit mother and baby alike," Katz said.
Dr. David Mendez, a neonatologist at Nicklaus Children's Hospital in Miami, said it isn't clear how much of the risk of a child's weight gain is tied to genetics or programming in the womb and how much is linked to the family's lifestyle.
"Trying to sort one from the other continues to be a challenge," Mendez said. "What is clear is that excessive weight gain during pregnancy has immediate consequences to mom and baby at the time of delivery."
Particularly, excessive weight gain exposes the infant to high levels of sugar and causes the infant to produce a lot of insulin in an attempt to balance sugar levels, he said.
"Exposure to high levels of insulin can affect the baby's metabolism during the transition from the womb," Mendez said.
Mendez said existing guidelines suggest how much weight a woman should gain during pregnancy.
For women of normal weight, an average of 20 to 35 pounds is adequate, he said. For women who are overweight, the range is 15 to 25 pounds. For obese women, the range is 11 to 20 pounds. And for women who are underweight, it's 28 to 40 pounds, he said.
"A healthy lifestyle before and during pregnancy means the best outcome for mom and baby," Mendez said.
