The rising acceptance and legalization of cannabis in the US correlates with increased cannabis use by pregnant women.
Research suggests fetal exposure to cannabis could result in negative metabolic outcomes in children during the early stages of life.
Based on evidence linking cannabis exposure to adverse neonatal outcomes, physicians should discourage cannabis use in pregnant women.
Increasing acceptance of cannabis use corresponds with a sharp rise in pregnant women using medical and non-medical cannabis.
The potential safety of fetal cannabis exposure as it pertains to neonatal outcomes has been little explored.
But current research suggests fetal exposure could have adverse metabolic effects on young children.
In exclusive interviews with MDLinx, three prominent specialists and researchers offered insights on the potential safety concerns of fetal cannabis exposure.
Effects of cannabis exposure during pregnancy
A study published in the Journal of Clinical Endocrinology & Metabolism evaluated the effects of fetal cannabis exposure on adiposity and glucose-insulin traits in early childhood.
The study included a subsample of 103 mother-child pairs from an ethnically diverse, pre-birth cohort. Researchers measured 12 cannabinoids/metabolites of cannabis in mothers’ urine at approximately 27 weeks’ gestation.
In follow-up at a mean age of 4.7 years, the investigators assessed fat mass, fat-free mass, and fasting glucose and insulin, dichotomizing the results for exposed vs non-exposed children.
At 27 weeks’ gestation, 15% of the women had detectable levels of a cannabinoid. Compared with unexposed offspring, children exposed to cannabis in the womb had significantly greater fat mass (1.0 kg; P < 0.01), fat-free mass (1.2 kg; P < 0.01), adiposity (2.6%; P = 0.04), and fasting glucose (5.6 mg/dL; P = 0.02) than those not exposed.
Increased risk in later life
In an MDLinx interview, study researcher Brianna Moore, PhD, said that previous studies have linked cannabis use during pregnancy with low birth weight, but such children who grow rapidly in infancy may have a higher risk of increased glucose and adiposity later in life.
An assistant professor in the Department of Epidemiology at the Colorado School of Public Health, Moore explained that these outcomes suggest cannabis exposure could increase the risk of metabolic disturbances in these children once they become older.
Moore added that the study does not make clear how fetal exposure to cannabis can impact an offspring’s metabolic health.
“The endocannabinoid system, which is highly sensitive to tetrahydrocannabinol, may play a role,” she noted. “There are other pathways involved in formation of fat calls that may also explain our findings.” She added that additional preclinical and epidemiology studies are needed to clarify the potential mechanisms.
Difficult decisions for mothers
Obstetrician-gynecologist and surgeon Greg Marchand, MD, of Marchand Institute for Minimally Invasive Surgery, told MDLinx there’s great uncertainty regarding the safety of marijuana use during pregnancy.
"As a result, not all obstetricians recommend cessation of marijuana during pregnancy," he said.
"Many pregnant women may feel as though they are being given mixed messages from providers. "
— Greg Marchand, MD
Marchand wasn’t involved in the study by Moore and colleagues but has published similar research, including a study which found associations between marijuana use during pregnancy and increased risks of low birth weight and neonatal intensive care unit admission.
Marchand said smoking marijuana, which some patients do to cope with anxiety, may do more harm than good to an infant. He added that emerging research findings will “force some difficult decisions for mothers who use marijuana to treat medical problems.”
Ryan Bogdan, PhD, an associate professor at Washington University in St. Louis, told MDLinx that it’s still unclear whether negative neonatal outcomes occur “as a causal consequence of prenatal cannabis exposure” and/or whether these outcomes may be attributable to a correlate of such exposure.
“It is possible that prenatal exposure to cannabis may reflect elevated predispositional risk for negative outcomes or be a correlate of other factors, including pregnancy difficulties that may be the real causal factors at play,” he said.
In 2021, Bogdan published a study in JAMA Psychiatry which suggested that exposure to cannabis and its correlated factors during the prenatal period may be associated with an increased risk of psychopathology during middle childhood.
What clinicians can do
Sarah Paul, a University Fellow from Washington University in St. Louis who was involved in the research study with Bogdan, told MDLinx, “Our interpretation of available evidence is that clinicians, cannabis dispensaries, and others should discourage [cannabis] use among women who are pregnant or are considering becoming pregnant, as is customary with other commonly used substances.”
However, Bogdan added, quitting substance use during pregnancy is not straightforward. "Physician support and empirical paradigms for quitting during pregnancy will be important," he said.
Marchand noted that it’s important for physicians—particularly those who care for pregnant women—to provide education on potential short- and long-term effects of cannabis use on children.
"We should make sure OB/GYN residency programs are discussing this in their curriculum. "
— Greg Marchand, MD
"Major healthcare organizations should also include this in their prenatal education materials,” he added.
Moore echoed Marchand’s comments, adding that patient education is key for helping reduce potential cannabis exposure risks in offspring. “Parents want what’s best for their children, so it’s important that the potential risks of cannabis use during pregnancy be widely communicated,” she said.
What this means for you
Cannabis use during pregnancy appears to be associated with adverse outcomes on infants. Physicians should discourage pregnant women from using cannabis products (among other substances, such as cigarettes and alcohol) during pregnancy. Avoid stigmatizing expectant mothers. Instead, focus on educating them on the risks vs educating them on the effects cannabis use can have on their offspring.