Heavy Marijuana Use During Pregnancy Could Endanger Baby’s Health, Study Finds

A study has found that using too much marijuana during pregnancy increases a baby's risk of being born prematurely and becoming underweight.

Following the legalization of recreational use of cannabis in different states across the U.S., the number of pregnant women using marijuana has increased, according to the National Institute on Drug Abuse (NIDA).

Although the study did not prove that marijuana itself could cause premature births and other effects, the risk of newborns developing complications was higher for pregnant women who heavily use cannabis. According to the study, babies were about 6% more likely to be born preterm and 13% more likely to become underweight, U.S. News has learned.

"There's a common misconception that because [marijuana] is a plant, it's safe," said Dr. Nora Volkow, the director of NIDA, which funded the study.

Yuyan Shi, an associate professor at the University of California, San Diego, noted that the research's results did not imply a direct cause-and-effect between marijuana use and fetal development issues. However, the results still suggested the importance of screening pregnant women for cannabis use disorder. Shi is the lead author of the study, which was published in the journal Addiction last Thursday.

The study, which entailed analyzing about 4.8 million births in California, focused on the effects of the plant on women diagnosed with cannabis use disorder to single out the effects of habitual marijuana use. Symptoms of cannabis use disorder include strong cravings for the drug, withdrawal symptoms and continued use despite it causing harm to one's relationships.

Of the women diagnosed with the disorder, the researchers found that their babies had a higher risk of being born early and underweight. The risk was even higher for women who also smoked tobacco. Among women who used cannabis while pregnant, around 80% also smoked cigarettes, the researchers found.

The study also revealed a grim finding. The babies of the women who heavily used marijuana during pregnancy had a 35% higher risk of dying during their first year of life.

"That was a surprising finding," Volkow said. "It will need to be replicated in other studies because that's the first time it's been reported."

Health experts continue to advise pregnant women that the safest course would always be to avoid taking unnecessary substances during pregnancy.