Marijuana can affect fetal development, even if used early in pregnancy

By Kara Murez

HealthDay reporter

TUESDAY, May 16, 2023 (HealthDay News) — As recreational use of marijuana increases, some pharmacies are recommending it as a remedy for morning sickness, but new research warns that its use during pregnancy may significantly affect fetal growth.

While fetal exposure to cannabis during early pregnancy may reduce birth weight, those effects may become more severe if use is continued throughout pregnancy, according to researchers at Central Michigan University in Mount Pleasant, Michigan.

“We show that even when marijuana use did not occur until the first trimester of pregnancy, birth weight was significantly reduced, by more than 150 grams (5.3 ounces) on average,” said senior study author Dr. Beth Bailey, a professor and director of public health research. “If that use continued into the second trimester, newborn head circumference was also significantly reduced.”

Newborn size is one of the strongest predictors of later health and development, said first author Dr. Phoebe Dodge, a resident pediatric resident at University Hospitals Rainbow Babies and Children’s Hospital in Cleveland.

The study, published May 16 in Frontiers in Pediatrics, found that babies exposed to cannabis continuously in the womb were almost 200 grams lighter at birth. Their head circumference was almost 1 centimeter smaller than that of babies who had not been exposed to cannabis.

“Size deficits were greatest in newborns exposed to marijuana during pregnancy,” Bailey said in a press release.

The study found that occasional cannabis use, such as morning sickness in the first trimester, may reduce fetal growth in the same way as continued use during pregnancy. This also applied to the use of cannabis before a woman knew about the pregnancy.

The study had no data on how much or how often participants used cannabis. The results were based on whether or not people took it at certain times during pregnancy.

The researchers were unable to determine whether there was an association between heavy use and more pronounced results in newborn growth. They said more research was needed.

“The best recommendation is that women should be advised to stop using marijuana before they become pregnant,” Dodge said.

Quitting as soon as possible after you become pregnant is the second best option, the study authors advised.

More information

The Office of Disease Prevention and Health Promotion has more information about a healthy pregnancy.

SOURCE: Frontiers in Pediatricspress release, May 16, 2023