Many overweight and obese women gain too much weight during pregnancy, further escalating up their already-increased risk of serious complications for themselves and their babies.
A new group of trials showed that pregnant women can safely limit their weight gain with diet and exercise interventions.
This is largest set of trials in the U.S. to target pregnancy weight gain of overweight and obese women. The trials included diverse socioeconomic groups, which means the findings are generalizable to a large population.
Seven teams of investigators recruited 1,150 participants for the LIFE-Mom trials (579 women had the lifestyle intervention, 571 had standard care), which ran from the second trimester to birth. Each trial offered a varied lifestyle intervention, but all aimed to improve diet quality and reduce calories, increase physical activity and incorporate behavior strategies such as self-monitoring.
Timing of diet and exercise important
This is an important study because it affirms that women can change behaviors to control the amount of weight gained in pregnancy.
However, the reduced weight gain – about four pounds per woman – did not result in fewer obstetrical complications, including caesarean sections, diabetes, hypertension and preeclampsia or change the average birth weight of the baby.
The researchers think that by the time these women are already in the second trimester, it may already be late to change important outcomes. To lower the risk of obstetrical complications, they may have to start changing their lifestyle before or immediately after they conceive.
Investigators are hopeful that there will be longer-term benefits of the interventions in the infants, such as less childhood obesity or fewer metabolic abnormalities such as childhood diabetes.
Recommended pregnancy weight gain
Overweight and obese women are a critical group to target, because they have higher rates of excess pregnancy weight gain and of retaining that weight postpartum. They also are more likely to have children who are obese.
About 62 percent of the women in the intervention groups, versus 75 percent in the control groups, exceeded the National Academy of Medicine recommendations for pregnancy weight gain. It is recommended that overweight women limit pregnancy weight gain to 15 to 25 pounds and obese women to 11 to 20 pounds, compared to 25 to 35 pounds for non-overweight women.
The advice doctors gave women about pregnancy weight gain has varied widely from decade to decade. In the 1950s, doctors often instructed their patients not to gain more than 15 pounds.
By the late 1970s and early 1980s, however, mothers weren't gaining enough weight and were having small babies, which could lead to developmental problems in childhood. Then doctors started encouraging women to gain more weight.
Risks of excess weight gain
In the early 2000s, physicians started noticing that excessive pregnancy weight gain was associated with certain pregnancy complications such as a higher incidence of high blood pressure, gestational diabetes and caesarean sections.
Excess maternal weight gain is also associated with bigger babies, who have an increased risk of obesity and childhood diabetes.
The clinical trials were conducted at Northwestern Medicine, California Polytechnic State University and Brown University, St. Luke's-Roosevelt Hospital and Columbia University, University of Puerto Rico, Washington University in St. Louis, Louisiana State University-Pennington Biomedical Research Center and the Phoenix Indian Medical Center/National Institute of Diabetes and Digestive and Kidney Diseases-Phoenix.
Source: Obesity, September 6, 2018.
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