High blood sugar in pregnancy ups child’s obesity risk

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A pregnant woman’s high blood sugar level is linked to a significantly greater long-term risk of obesity in her child—even more than a decade later, a new study reports. The higher the woman’s blood sugar, the greater the risk of her child being obese.

“The mother’s blood sugar level during pregnancy is an independent contributor to the child’s weight and risk of being obese later in childhood,” says corresponding study author Boyd Metzger, professor emeritus of medicine in endocrinology at Northwestern University Feinberg School of Medicine.

“We’ve known for a long time that family characteristics predict a lot about how you’re going to look…,” Metzger says. “This is above and beyond the mother’s weight. This takes into account all those other factors.”

Higher risk for moms, too

Mothers with higher-than-normal blood sugar during pregnancy—even if not high enough to meet the definition for gestational diabetes commonly used in the US today—also were significantly more likely to have developed type 2 diabetes a decade after pregnancy than their counterparts without high blood sugar.

Researchers have known that treating high blood sugar during pregnancy reduces problems for the newborn and mother. Lowering a mother’s blood sugar reduces the birth weight of the child, as well as the risk of pre-eclampsia, a potentially life-threatening condition in which the mother has high blood pressure that affects her and the baby.

But prior to this study, which appears in the Journal of the American Medical Association, scientists did not know that risks related to blood sugar during pregnancy continue into childhood. And they still don’t know if treating the mother reduces these longer-term risks. Future studies will need to help answer these questions, Metzger says.

“We don’t know the mechanisms of how these long-term changes happen,” Metzger says. “We suspect epigenetic changes are likely to be influencing these long-term outcomes and those changes begin quite early in pregnancy.”

Harmful outcomes

With major increases in obesity worldwide, the frequency of all forms of diabetes, including gestational diabetes, has increased. New criteria based on the results of Metzger’s original HAPO Study in 2012 further increases the number of women with gestational diabetes.

The HAPO-FUS (Hyperglycemia and Adverse Pregnancy Outcomes-Follow-Up Study) evaluated children 10 to 14 years after birth in 10 clinical centers in seven countries: the US, Canada, Israel, the UK, Hong Kong, Thailand, and Barbados. The study included 4,697 mothers and 4,832 children.

Investigators used multiple methods to determine degrees of a child being overweight. Simply calculating Body Mass Index (BMI) in kids has some limitations because a muscular young person will have a fairly high BMI but is not overweight.

Clinical sites used a bod pod that more accurately calculates the percent of fat tissue. In addition, investigators measured the waist or hip as well as the thickness of the skin folds, which all correlate with how obese someone is, Metzger says.

“The children of moms with gestational diabetes and higher blood sugar were higher in all these categories,” Metzger says.

“The HAPO-FUS results are important because they demonstrate that even women with mild hyperglycemia during pregnancy and their offspring are at risk of harmful maternal and child health outcomes, potentially increasing the number of women and children at risk of acquiring lifelong chronic medical conditions,” says coauthor Wendy Brickman, an associate professor of pediatric endocrinology at Feinberg and a pediatrician at Ann and Robert H. Lurie Children’s Hospital of Chicago.

“Research is needed to identify interventions that will improve the health outcomes of these women and children.”

The National Institute of Diabetes and Digestive and Kidney Diseases and the Eunice Kennedy Shriver National Institute of Child Health and Human Development funded the work.

Source: Northwestern University