For obese women, there’s a catch on weight control during pregnancy

Pregnant women who are obese or overweight are at increased risk of complications, such as needing cesarean sections, developing gestational diabetes and even the dangerous high blood pressure known as preeclampsia. Diet and exercise, researchers say, can help them safely control their weight gain during pregnancy. But there is a catch. The women in a recent study who lost weight — about four pounds on average — after they were at least nine weeks into their pregnancies did not have fewer obstetric complications. Researchers are concluding that to lower risk of complications, women might have to change their behaviours before or immediately after they conceive.

“We think that by the time these women are already in the second trimester, it may already be late to change important outcomes,” said Alan Peaceman, lead author and chief of maternal fetal medicine at Northwestern University.

Seven clinical centres including Brown and Columbia universities recruited 1,150 pregnant women for the trial and split them into a control group and an intervention group. The second group focused on reducing calories, increasing physical activity and incorporating behaviour changes such as self-monitoring. The trial, funded by the National Institutes of Health, followed participants between nine to 15 weeks pregnant through the birth of their child.

The study was published last week in the journal Obesity.

Most American women of childbearing age are overweight or obese. These women are more likely to gain excess weight in pregnancy, and to retain those pounds after childbirth. Their children, too, are more likely to be obese and face childhood diabetes than are the children of thinner women.

The National Academy of Medicine recommends that women who are not overweight limit their pregnancy weight gain to 25 to 35 pounds. Women who are overweight should gain no more than 15 to 25 pounds and obese women should not gain more than 11 to 20 pounds.