Prenatal Cannabis Use Does Not Increase Risk for Autism in Children

Use of cannabis in early pregnancy is not associated with increased risk for offspring autism spectrum disorder (ASD), according to study results published in JAMA Network Open.

There is a growing perception that using cannabis in pregnancy, as opposed to other prescription medications, poses a lower risk. Researchers from Kaiser Permanente Northern California (KPNC) sought to examine the association between early pregnancy cannabis use and ASD in children aged 12 years and younger.

For the cohort study, the researchers used data from the KPNC integrated health system. Pregnant individuals (N=146,296) with a singleton pregnancy (n=178,948) between 2011 and 2019 self-reported whether they used cannabis and/or had a urine toxicology test for tetrahydrocannabinol (THC). The primary outcome was offspring diagnosis of ASD through age 12 or 2022 on the basis of exposure to cannabis in early gestation.

A total of 8486 pregnant individuals screened positive for cannabis. Among these individuals, 39.2% were non-Hispanic White; 33% aged 18 to 24; 40.8% lived in the most deprived neighborhood deprivation quartile; 55% were nulliparous; and 64.4% initiated prenatal care in the first 2 months of pregnancy. 

Across the entire study cohort, during a median follow-up of 3.7 years, 3.6% of children were diagnosed with ASD at a median age of 3. Of the children diagnosed with ASD, 22.5% were girls and 77.5% were boys.

The rate of ASD among children with cannabis exposure vs those without were 4.4% and 3.6%, respectively. In the unadjusted analysis, cannabis exposure was associated with increased risk for ASD (hazard ratio [HR], 1.25; 95% CI, 1.10-1.42; P <.05).

However, in the model adjusted to reflect maternal sociodemographic characteristics, cannabis exposure was not significantly associated with ASD risk (HR, 1.10; 95% CI, 0.87-1.38) nor was the association significant in the fully adjusted models (HR, 105; 95% CI, 0.84-1.32).

Stratified by cannabis use patterns, the rates of ASD were 4.9% with daily use, 4.7% with weekly use, 3.5% with monthly use or less, and 4.6% with unknown use frequency.

ASD risk was associated with daily (HR, 2.12; 95% CI, 1.19-3.78; P <.05) and unknown frequency (HR, 1.42; 95% CI, 1.06-1.91; P <.05) use in the unadjusted models but not in the minimally adjusted models.

In the fully adjusted model and stratified by cannabis use reporting method, cannabis exposure was not associated with childhood ASD in pregnancies with self-reported use (HR, 0.89; 95% CI, 0.64-1.23) or urine toxicology positivity (HR, 1.10; 95% CI, 0.86-1.41).

Stratified by child gender, no relationship between cannabis exposure and ASD risk was observed among boys (aHR, 1.01; 95% CI, 0.77-1.32) or girls (aHR, 1.19; 95% CI, 0.77-1.85).

The researchers concluded, “[M]aternal prenatal cannabis use was not associated with child ASD after adjusting for potential confounders, including sociodemographic characteristics, other noncannabis substance use and maternal comorbidities.”

This study was limited by only having access to one cannabis assessment during pregnancy and the lack of data about THC dosing or ingestion method.

This article originally appeared on Psychiatry Advisor