MONDAY, July 13, 2020 (HealthDay News) -- Kids whose moms used pot while pregnant may end up with sleep problems years later, a new study suggests.
Looking at thousands of 9- and 10-year-olds, University of Colorado researchers found that children were more likely to have trouble falling asleep or staying asleep if their mother had used marijuana prenatally.
"While not explicitly causal, the results are consistent with potential long-term effects of prenatal cannabis exposure on childhood sleep, so mothers should avoid cannabis while pregnant, similar to alcohol, tobacco and other substances," said lead researcher Evan Winiger. He's with the Institute for Behavioral Genetics at the University of Colorado, Boulder.
About 7% of pregnant women use pot, and that number is growing as more women try it to alleviate morning sickness, the researchers said in background notes.
The new report, involving nearly 12,000 children, used data from the Adolescent Brain Cognitive Development study, a long-term project funded by the U.S. National Institutes of Health.
In that study, mothers were asked if they had used marijuana while pregnant and how often. They were also asked how well their children slept.
In all, nearly 700 mothers said they used marijuana while pregnant -- 184 used it daily and 262 used it twice or more a day, the findings showed.
After taking into account factors such as the mother's education, marital status, family income and race, the researchers found a clear link between pot use during pregnancy and a child's sleep problems.
Those who used marijuana were significantly more likely to have children who had symptoms of clinical sleep issues, such as trouble falling asleep and maintaining sleep, waking up during the night and excessive fatigue during the day, Winiger said.
The researchers also found that the more often moms-to-be used marijuana, the more likely their kids were to be sleepy during the day and to struggle getting up in the morning.
It's not clear how a pregnant woman's marijuana use can cause her child to have sleep problems, but Winiger made some speculations.
The fetal brain has areas that respond to cannabis, he said. These receptors might affect a child's sleep cycle, and as cannabis binds to them, it changes how the brain is wired, Winiger said.
He is also not sure that there is any benefit to using marijuana during pregnancy to reduce the symptoms of morning sickness.
"I am unaware of any studies that show benefits of using cannabis while pregnant in terms of morning sickness," Winiger said.
"I believe there is decent research showing cannabis can help with nausea, and perhaps that is where the idea that it helps with morning sickness comes from. But we should be cautious and hesitant to extend that to a sensitive period such as pregnancy," Winiger said.
Dr. Ruth Milanaik is director of neonatal developmental follow-up programs at Cohen Children's Medical Center in New Hyde Park, N.Y. She agreed that mothers-to-be should avoid using marijuana.
"While there is no causality implied in this study, this is a concerning finding considering research that shows the wide-ranging importance of sleep on body and mind functioning," she said.
"Considering these findings and previous warnings from the American College of Obstetricians and Gynecologists, pregnant women should continue to minimize exposure to all cannabis products," Milanaik said.
The report was published online June 28 in the journal Sleep Health.
For more on pot and pregnancy, see the U.S. Centers for Disease Control and Prevention.
SOURCES: Evan Winiger, MA, Institute for Behavioral Genetics, University of Colorado, Boulder; Ruth Milanaik, DO, director, neonatal developmental follow-up programs, Cohen Children's Medical Center, New Hyde Park, N.Y.; June 28, 2020, Sleep Health, online