The study showed that mothers who reported sleeping five hours or less per day when their babies were six months old had a threefold higher risk for substantial weight retention (11 pounds or more) at their baby's first birthday than moms who slept seven hours per day.
The study, by Kaiser Permanente and Harvard Medical School / Harvard Pilgrim Health Care, is the first to look at the impact of sleep deprivation on postpartum weight retention.
"We've known for some time that sleep deprivation is associated with weight gain and obesity in the general population, but this study shows that getting enough sleep - even just two hours more - may be as important as a healthy diet and exercise for new mothers to return to their pre-pregnancy weight," said Erica P. Gunderson, PhD, an investigator at the Kaiser Permanente Division of Research in Oakland and the lead author of the study.
It was also found that mothers who slept fewer hours at one year postpartum than they did at six months postpartum had twice the risk of substantial weight retention.
Other studies have shown that persistent sleep deprivation causes hormonal changes that may stimulate appetite. Shorter sleep duration has not only been linked to obesity in women, but coronary artery disease and diabetes as well.
For the new study, researchers looked at 940 women participating in Harvard's Project Viva, an observational, longitudinal cohort study of prenatal and postnatal health.
The women, whose median age was 33 years old and were a mix of Caucasian, African American and Hispanic, were queried about their sleep habits and weight at the six-month and one-year postpartum assessments. Forty-seven percent of the women were first-time mothers, 37 percent had two children, and 16 percent had three or more children.
"A new baby's first year at home is a hard adjustment for everyone. That's why Kaiser Permanente has integrated our care for moms with our care for babies. We give moms tools and services to make it easier to juggle everything, and get back into shape: a pregnancy e-newsletter, newborn clubs, online health encyclopedia, online programs, podcasts, videos, weight and exercise programs, and discounts for gym memberships and Weight Watchers enrollment," said Tracy Flanagan, MD, Director of Women's Health, Kaiser Permanente Northern California.
"But the best advice of all for moms with new babies is ask for help, get support and take care of yourself," Flanagan added.
The study is published in the November issue of the American Journal of Epidemiology.