A new study suggests that poor-quality sleep during the third trimester of pregnancy can increase the odds of weight gain and metabolic abnormalities in offspring once they reach adulthood.
The researchers linked the excess weight and changes in metabolism to epigenetic modifications that reduce expression of the gene for adiponectin-a hormone that helps regulate several metabolic processes, including glucose regulation. Lower levels of adiponectin correlate with increased body fat and reduced activity.
"Disrupted sleep is a common problem during the final trimester of a pregnancy," study director, sleep specialist David Gozal, MD, the Herbert T Abelson professor of pediatrics at the University of Chicago said.
"For some women, sleep fragmentation, especially sleep apnea, can be profound. We wanted to devise a system that enabled us to measure the potential impact of fragmented sleep on the fetus, which is uniquely susceptible so early in life," he said.
To test this in humans could take 50 years, so Gozal's team devised experiments using pregnant mice. The researchers interrupted sleep for half of the mice during days 15 through 19 of pregnancy, the mouse equivalent of the third trimester.
During the day, when mice normally sleep, a motorized brush swept through those cages every two minutes, forcing the mouse mothers-to-be to wake up briefly, step over the brush and go back to sleep. Pregnant mice in the other cages were not disturbed.
Newborns from both groups weighed the same at birth and initially had normal feeding habits and growth trajectories, but diverged in adulthood.
"For several weeks after weaning all the mice seemed fine," Gozal said. "But after 16 to 18 weeks - the mouse equivalent of early middle age - we noticed that the male mice born to moms with fragmented sleep were eating more. Their weights started creeping up."
The study is published online in the journal Diabetes.
