In Utero Cannabis Exposure Linked To Psychopathology Risk In Children Ages 9-11

Cannabis use by women who know they're pregnant was associated with increased risk of offspring psychopathology at ages 9-11 in a cross-sectional study, suggesting such use should be discouraged.

"Things became very interesting" when researchers looked at potentially confounding factors such as socio-economic status, prenatal tobacco, alcohol, and vitamin exposure, whether the pregnancy was planned, familial psychopathology, and child substance experimentation, Dr. Ryan Bogdan of Washington University in St. Louis told Reuters Health.

"All associations with prenatal (cannabis) exposure that occurred prior to maternal knowledge of pregnancy were no longer significant," he said. "This suggests that the adverse outcomes associated with prenatal cannabis exposure during these early stages of pregnancy are not independent of these confounding factors."

"However, when we look at exposure after maternal knowledge of pregnancy (approximately seven weeks post-pregnancy on average), associations with psychopathology remained," he said. "During middle childhood, kids who were exposed to cannabis in utero had more psychotic-like experiences (PLEs), more problems with impulsivity and attention, and social problems characteristic of early neurodevelopmental disorders, such as autism."

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"While these data in no way demonstrate that prenatal cannabis exposure causes these problems, they increase the plausibility that prenatal cannabis exposure may contribute to them by showing associations that are independent of confounds," he said.

Dr. Bogdan and colleagues studied data from the baseline session of the ongoing longitudinal Adolescent Brain and Cognitive Development. As reported in JAMA Psychiatry, among 11,489 children (52.2% boys; mean age, 9.9 years), 655 (5.7%) were exposed to cannabis prenatally.

Before covariate adjustment and compared with no exposure, cannabis exposure before (3.6%) and after (2.1%) maternal knowledge of pregnancy was associated with greater psychopathology characteristics in offspring (ie, PLEs, internalizing, externalizing, attention, thought, and social problems), as well as sleep problems, BMI, cognition, and smaller gray matter volume.

Exposure only after knowledge of pregnancy was associated with lower birth weight as well as lower total intracranial volume and white matter volumes relative to no exposure and exposure only before knowledge.

After accounting for potentially confounding covariates, exposure after maternal knowledge of pregnancy remained associated with greater PLEs and externalizing, attention, thought, and social problems, as Dr. Bogdan noted. However, exposure only prior to maternal knowledge of pregnancy did not differ from no exposure on any outcomes.

Dr. Bogdan said, "My take on these data is that cannabis use among pregnant women should be discouraged." However, he added, "we need experimental non-human animal models, replication, and unique study designs (e.g., siblings discordant for prenatal exposure) to inform causality."

Dr. Stephanie Zeszutek, Course Director for Physical Diagnosis in the Department of Primary Care at Touro College of Osteopathic Medicine - Middletown Campus, told Reuters Health by email that the findings "appear feasible."

"Due to the easing of the legalities surrounding cannabis use, and its increasing use, both socially and medicinally," she said, "women should be counseled prior to and during pregnancy to increase their awareness of the short- and long-term risks of cannabis use on their offspring, just as we counsel on the adverse effects of alcohol and nicotine use in pregnancy. Cannabis use during pregnancy should be discouraged and alternative management options should be offered if medicinal use is a factor in the decision to use cannabis in pregnancy."

Dr. Liesl Smith, an obstetrician-gynecologist on the medical staff at Texas Health Dallas, also commented by email. "A study released several years ago had researchers pretending to be women suffering from morning sickness calling dispensaries in Colorado asking if it was OK/safe/recommended to use marijuana to treat morning sickness, and a large number of women were given incorrect information. Often, they were told it was safe and were not advised to discuss this with their prenatal health care provider."

Like Dr. Zeszutek, she advises clinicians to discuss the findings with all women of childbearing age. "Clinicians should approach patients with this information in an educational, collaborative, helpful way," she said. "We should be clear our intent is to improve the health and well-being of the mom and child. There is nothing punitive or judgmental from a health care provider that will improve the patient's care."

—Marilynn Larkin

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