Two large studies looked for developmental disorders and autism in children of mothers who used cannabis in early pregnancy
New analyses of maternal cannabis use during early pregnancy find no evidence of increased risk of early developmental delays up to age 5 or of autism spectrum disorder. The studies were published in JAMA Network Open.
“Our study on developmental delays is the first to examine clinical diagnoses of speech and language disorders, motor delays, and global developmental delays and we looked up to age 5, longer than other studies have done,” said lead author Lyndsay Avalos, PhD, MPH, a research scientist with the Kaiser Permanente Division of Research (DOR).
There are many potential health outcomes for mothers and babies related to prenatal cannabis use that are being studied, and the findings from both studies add to an early but growing body of evidence, Avalos said. The study team has previously reported about possible maternal health risks and poor outcomes for infants, such as preterm birth.
Results from both analyses are also consistent with another recent study from the same researchers, published in the Journal of Developmental and Behavioral Pediatrics, that found no increased risk of attention deficit hyperactivity disorder or disruptive behavior disorders, up to age 11, in the children of mothers who used cannabis in early pregnancy.
“These studies add to our limited knowledge about child developmental outcomes associated with maternal prenatal cannabis use by using a well-established population for studying health effects of cannabis use in pregnancy,” Avalos said.
While reassuring, the findings do not negate previous research showing an increased risk of adverse maternal and neonatal outcomes related to prenatal cannabis use, said senior author and DOR Research Scientist Kelly Young-Wolff, PhD, MPH. “We recommend that pregnant individuals avoid cannabis use during pregnancy, consistent with guidelines from national medical organizations.”
The studies are similar in design but differ in some details. The early childhood developmental delays paper is a retrospective look at 119,976 mother-child duos among patients of Kaiser Permanente Northern California (KPNC); the children were born between 2015 and 2019 and followed for up to five-and-a-half years.
For this study, researchers looked in patient medical records for diagnoses of speech and language disorders, motor delays, or global delays. Diagnoses are made based on KPNC’s standard surveillance for developmental delays in pediatric care. Mothers were screened for cannabis use through a questionnaire and urine toxicology test when they began prenatal care, usually around 8 to 10 weeks’ gestation. No increased risk of early childhood developmental delays was found related to maternal prenatal cannabis use.
The second study, which focused on risk of autism, included 178,948 children born between 2011 and 2019 to 146,296 KPNC patients. Child autism spectrum disorder diagnoses were obtained from medical records and based on KPNC’s universal pediatric autism screening, and maternal cannabis use was assessed through prenatal care screening. The study found 3.6% of children were diagnosed with ASD. There was no relationship found with maternal prenatal cannabis use.
The findings from both studies could be helpful to pediatricians, said co-author Meghan Davignon, MD, a developmental pediatrician with The Permanente Medical Group and KPNC’s regional medical director of pediatric developmental disabilities. “If the studies found children exposed to marijuana were at higher risk for developmental delays or autism, we might want to monitor these patients more closely,” she said. “But these findings suggest that currently recommended universal screening practices may be adequate.”
Reporting “negative” findings
It is important for epidemiologists to report null findings — when there is no observed effect —so health care resources can be focused where they are most needed, Avalos said. “For example, if we thought prenatal cannabis use was associated with autism spectrum disorder, you might put resources toward early identification of children whose parent used cannabis while pregnant. If there does not appear to be a risk, you can use those resources elsewhere. And you can save parents that additional worry.”
The studies also advance the field by providing updated evidence based on current cannabis use. “While many of the prior studies were based on prenatal cannabis use in the 1970s, our study is based on newer data that more accurately reflects the strength of cannabis products being used today,” Young-Wolff said.
Additional research is needed to explore if use of cannabis later in pregnancy could be related to increased risk of developmental delays or autism spectrum disorder, as these analyses pulled from data on cannabis use early in pregnancy.
As the children in this study grow older, the research team intends to look at other health outcomes that can appear later in childhood or adolescence, such as mental health problems, substance use, and cardiovascular disease, Avalos said.
The findings coming from DOR’s prenatal cannabis team’s work are also helpful for KPNC’s Early Start prenatal health program, said its regional medical director and co-author on both papers, Deborah Ansley, MD. “Women need specific information about health risks to be able to make informed decisions about substance use in pregnancy. This ongoing research project continues to produce evidence that is filling in that picture.”
The studies were funded by the National Institute on Drug Abuse.
Additional co-authors on the developmental delays study were Nina Oberman, MPH, Stacey E. Alexeeff, PhD, Lisa A. Croen, PhD, and Sara R. Adams, MPH, of DOR; Christina D. Chambers, PhD, MPH, of the University of California, San Diego; and Kristin Steuerle, MD, of The Permanente Medical Group.
Additional co-authors on the autism study were Mahlet Shunkute, MS, Alexeeff, Oberman, Croen, and Adams, of DOR; and Carley Castellanos, LMFT, of Kaiser Permanente Northern California.
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About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 600-plus staff is working on more than 450 epidemiological and health services research projects. For more information, visit divisionofresearch.kaiserpermanente.org or follow us @KPDOR.
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