Cannabis use during pregnancy increases risks for babies

Key takeaways:

• Prenatal cannabis exposure was linked to low birth weight, small for gestational age, preterm birth and NICU admission.
• In utero cannabis exposure was not significantly associated with respiratory support.

In utero cannabis exposure was linked to increased risks for low birth weight, small for gestational age, preterm birth and NICU admission, researchers reported in the American Journal of Obstetrics and Gynecology.

“Findings from this study improve upon the current body of evidence demonstrating an association between maternal prenatal cannabis use and adverse birth outcomes,” Lyndsay A. Avalos, PhD, MPH, senior research scientist at Kaiser Permanente Northern California Division of Research, told Healio. “Health care providers should discuss the risks of cannabis use in pregnancy with their patients through open, nonjudgmental conversations so patients can balance the pros and cons of various methods of managing conditions during pregnancy.”

Avalos and colleagues conducted a population-based retrospective cohort study of data from 364,924 singleton births that occurred from 2011 to July 2020 among Kaiser Permanente Northern California members. All pregnancies were screened for cannabis use with in utero cannabis exposure defined as self-report since becoming pregnant and/or a positive urine toxicology test for cannabis during at any time in pregnancy and frequency of use.

The primary outcomes included neonatal outcomes such as low birth weight, small for gestational age, preterm birth, NICU admission and infant respiratory support.

Overall, 6.2% of infants had in utero cannabis exposure. In utero cannabis exposure was associated with a greater likelihood of low birth weight (adjusted OR = 1.2; 95% CI, 1.12-1.28), small for gestational age (aOR = 1.24; 95% CI, 1.18-1.3), preterm birth (aOR = 1.06; 95% CI, 1-1.13) and NICU admission (aOR = 1.06; 95% CI, 1.01-1.11) when adjusting for potential confounders.

In addition, researchers observed a suggestive association between early preterm birth less than 34 weeks gestation and in utero exposure (aOR = 1.11; 95% CI, 1-1.23; P = .055). Researchers noted no significant association between in utero cannabis exposure and respiratory support.

In a dose-response analysis, low birth weight and small for gestational age likelihoods increased with the frequency of prenatal cannabis use. The sensitivity analyses also supported increased low birth weight and small for gestational age likelihood, but associations with other neonatal outcomes were not significant.

According to Avalos, the researchers are currently evaluating the effects of maternal prenatal cannabis use on pregnancy conditions and developmental outcomes of the child.

“Future research on the effects of the mode of cannabis administration, cannabis potency and the timing and duration of cannabis exposure is needed,” Avalos said. “Additionally, large well-designed studies are needed to investigate additional potential health effects of cannabis use during pregnancy on the mother and child.”

For more information:

Lyndsay A. Avalos, PhD, MPH, can be reached at lyndsay.a.avalos@kp.org.