Cannabis use in pregnancy may raise infant health risks

A large study of more than 360,000 mothers and infants found increased risk of low birth weight and admission to the neonatal intensive care unit (NICU) for babies whose mothers used cannabis during pregnancy.

The findings align with previous research suggesting a connection between prenatal cannabis use and low birthweight babies, and advice from the American College of Obstetricians and Gynecologists that pregnant patients avoid cannabis in pregnancy.

The researchers also found a "dose-response" relationship, meaning increasing risk of infant health risks with more frequent reported use of cannabis.

The analysis used health records from 364,924 infants born to Kaiser Permanente Northern California (KPNC) members between January 2011 and July 2020. Of these, 6.2% of the infants were exposed to cannabis in utero. Information about cannabis use was obtained from a self-report prenatal screening questionnaire and a urine toxicology test.

The study found statistically significantly greater odds of low birthweight, baby that is small for gestational age, preterm birth, and admission to a NICU. The paper is published in the American Journal of Obstetrics and Gynecology.

"Our analysis adds new concerns about the potential for preterm birth and NICU admission, which are associated with immediate, highly stressful situations for the family as well as long-term adverse outcomes for the child," said lead author Lyndsay Avalos, Ph.D., MPH, a research scientist with the Kaiser Permanente Division of Research.