A recent study published in the Journal of Developmental & Behavioral Pediatrics found that children whose mothers used cannabis in early pregnancy did not have an increased risk of being diagnosed with attention deficit hyperactivity disorder or disruptive behavior disorders by age 11. However, the authors caution that these findings do not dismiss the established risks to maternal and newborn health that other studies have linked to cannabis use during pregnancy.
Prenatal cannabis use has become a growing concern, with increasing numbers of pregnant individuals in the United States reporting cannabis use for issues such as anxiety, mood disturbances, or pregnancy-related symptoms. Despite some perceptions that cannabis is a safe remedy, studies have shown that it can cross the placenta and potentially impact fetal development.
“Our team has been studying prenatal cannabis use for nearly a decade. During this time, we have seen important increases in rates of cannabis use during pregnancy, corresponding with spreading legalization across the United States and rising perceptions of cannabis safety,” said study author Kelly Young-Wolff, a research scientist at Kaiser Permanente Division of Research.
“Our time-series study of more than 300,000 pregnancies at Kaiser Permanente Northern California screened for prenatal cannabis use from 2012 to 2019 published in JAMA Health Forum last week found that the implementation of recreational cannabis legalization in California was associated with an immediate rise in rates of prenatal cannabis use. Local policy analyses indicated that this rise was limited to pregnant individuals living in cities and counties that permitted versus banned cannabis retailers.”
“Importantly, our research has also added to a growing body of evidence indicating that cannabis use during pregnancy is associated with increased risk of adverse neonatal outcomes, including preterm birth, lower birthweight, small for gestational age babies, and neonatal intensive care unit admission. Our recent research has also shown an association between prenatal cannabis use and adverse maternal pregnancy outcomes. We are now examining how maternal prenatal cannabis use relates to adverse health outcomes in childhood.”
The research team conducted a retrospective study of a large cohort of pregnant individuals and their children. This study involved 141,570 children born between 2011 and 2018 to 117,130 mothers enrolled in the Kaiser Permanente Northern California healthcare system. All participants underwent universal cannabis screening when they began prenatal care, typically around the eighth to tenth week of pregnancy.
The screening involved two components: a self-reported survey where participants disclosed any cannabis use since becoming pregnant and a urine test to detect recent cannabis use. Researchers classified prenatal cannabis exposure in four ways: (1) any cannabis use (indicated by either self-report or a positive urine test), (2) self-reported cannabis use, (3) a positive urine test, and (4) frequency of cannabis use (categorized as daily, weekly, or monthly or less).
The researchers then tracked the children’s medical records to identify any diagnoses of attention deficit hyperactivity disorder or disruptive behavior disorders up to age 11. The team used statistical models to evaluate potential associations between prenatal cannabis use and these childhood diagnoses. These models controlled for a range of maternal factors that might influence child development, such as socioeconomic status, other substance use during pregnancy, timing of prenatal care initiation, and any pre-existing health conditions.
About 4.6% of the pregnant individuals in the study screened positive for cannabis use. Among these participants, cannabis use was further broken down by frequency, with 0.4% using cannabis daily, 0.5% weekly, 1.1% monthly or less, and 2.7% having an unknown frequency. Around 7.7% of the children in the overall sample were diagnosed with attention deficit hyperactivity disorder, while 6.8% were diagnosed with disruptive behavior disorders.
The analysis found no increased likelihood of these disorders among children exposed to cannabis in early pregnancy. For disruptive behavior disorders, there was a slight but statistically significant trend suggesting a lower risk associated with prenatal cannabis exposure when detected through urine testing, though this was not observed with self-reported use. The frequency of cannabis use, whether daily, weekly, or monthly or less, did not affect the outcomes for these childhood disorders.
“Using data from a large sample of pregnant people screened for prenatal cannabis use as part of standard prenatal care, prenatal cannabis use was not associated with an increased risk of offspring attention deficit hyperactivity disorder or disruptive behavior disorders,” Young-Wolff told PsyPost. “However, prenatal cannabis use is a risk factor for adverse fetal and neonatal outcomes, and there are many important reasons for quitting cannabis use when pregnant. Clinicians should continue to educate patients about the potential health risks and provide patient-centered support to help patients make informed decisions about prenatal cannabis use.”
While these findings offer some reassurance, the authors note several limitations. First, the study focused on a sample from a single healthcare system, which might not reflect the experiences of all populations, especially those who do not receive prenatal care or are uninsured. Additionally, the cannabis exposure data only covered early pregnancy; it did not account for whether participants continued to use cannabis later in pregnancy or the type and potency of the cannabis consumed. These factors could impact a fetus differently and might yield different outcomes in other groups.
Another important limitation is the relatively young age of the children at the study’s end. Behavioral and attention disorders can sometimes emerge later in childhood or adolescence, so it remains possible that longer-term follow-up could reveal different results.
The study authors encourage future research to explore cannabis use across all pregnancy trimesters, including dosage and method of consumption. Examining how these factors influence neurodevelopmental outcomes could offer a clearer understanding of the long-term impacts of prenatal cannabis exposure.
“Research suggests that pregnant people are bombarded with inaccurate messages from social media, cannabis retailers, and peers suggesting that cannabis use during pregnancy is safe,” Young-Wolff explained. “Further, studies have shown that many pregnant patients turn to cannabis to self-medicate pregnancy-related symptoms, such as depression or morning sickness. It is important to remember that pregnant individuals care about having a safe pregnancy and are seeking information about the potential risks associated with using cannabis during pregnancy.”
“While we did not find an association between prenatal cannabis use and childhood ADHD or disruptive behavior disorders in this study, there is a growing body of evidence indicating that cannabis use during pregnancy is associated with increased risk for adverse neonatal and maternal outcomes. If pregnant individuals are considering using cannabis during pregnancy to self- medicate pregnancy-related symptoms, we encourage them to discuss those symptoms with their doctor and use interventions recommended by clinical practice guidelines. If pregnant individuals are not willing to quit using cannabis, we recommend that they try to use it less frequently.”
“Importantly, with legalization, there has been an increase in alternative forms of cannabis administration, including vaping and edibles,” Young-Wolff continued. “The relative risks associated with different routes of cannabis administration during pregnancy are unknown and warrant additional research.”
“We are now screening all pregnant patients in Kaiser Permanente Northern California for modes of cannabis use during pregnancy, and our team received a large grant from the National Institute on Drug Abuse to study how different modes of cannabis use are related to maternal health outcomes during pregnancy. Our focus group data indicate that pregnant patients want information about whether certain modes of cannabis use are more harmful than others, and we hope to be able to answer this question with our future research.”
The study, “Prenatal Cannabis Use and Offspring Attention Deficit Hyperactivity Disorder and Disruptive Behavior Disorders: A Retrospective Cohort Study,” was authored by Kelly C. Young-Wolff, Kevin Kong, Stacey E. Alexeeff, Lisa A. Croen, Nina Oberman, Harshal Kirane, Deborah Ansley, Meghan Davignon, Sara R. Adams, and Lyndsay A. Avalos.
