As more states legalize marijuana and social media touts its use for morning sickness, the nation’s pediatricians caution the drug may not be harmless.
With marijuana use more commonly reported by women who are pregnant or breastfeeding, a new American Academy of Pediatrics (AAP) report calls for more research on possible developmental effects on children. Highlighting emerging evidence that marijuana likely is not harmless as widely assumed, the AAP recommends women avoid the drug while pregnant or nursing a child.
The clinical report, “Marijuana Use During Pregnancy and Breastfeeding: Implications for Neonatal and Childhood Outcomes,” published in the September 2018 Pediatrics, cites statistics showing that more babies than ever are being exposed to marijuana.
With marijuana now legal for medical or recreational use in more than half of U.S. states, statistics show its use rising. Marijuana use among pregnant women increased by 62 percent between 2002 and 2014, nationally. Meanwhile, marijuana has become more potent, with average concentrations of the psychoactive compound tetrahydrocannabinol (THC) more than quadrupling since the 1980s.
“The fact that marijuana is legal in many states may give the impression the drug is harmless during pregnancy, especially with stories swirling on social media about using it for nausea with morning sickness,” said Sheryl A. Ryan, MD, FAAP, a lead author of the report and Chair of the AAP Committee on Substance Use and Prevention.
“But in fact, this is still a big question. We do not have good safety data on prenatal exposure to marijuana. Based on the limited data that does exist, as pediatricians, we believe there is cause to be concerned about how the drug will impact the long-term development of children,” Dr. Ryan said.
THC, the chemical in marijuana mostly responsible for its psychoactive effects, readily crosses the placenta and enters the rapidly developing brain of the fetus. Research has shown that THC gets into breastmilk, including a study published in Pediatrics Aug. 27 that found THC present in breastmilk up to six days after the last use.
Less is known about what happens once marijuana gets in a baby’s system, according to the AAP, but the studies that do exist consistently suggest links between prenatal exposure and possible neurodevelopment effects. These include harm to children’s executive function skills including concentration, attention, impulse control and problem-solving. Some studies also reveal a possibly higher risk of substance use disorder and mental illness among teens and adults who had prenatal exposure to marijuana.
“Many of these effects may not show up right away, but they can impact how well a child can maneuver in the world,” Dr. Ryan said. “Children’s and teens’ ability to manage their time, school work, and jobs might all be harmed down the line from marijuana use during their mother’s pregnancy.”
Existing research also shines light on the mechanisms behind these possible effects. The AAP report describes evidence suggesting THC attaches to and essentially “hijacks” and disrupts neurotransmitters in the brain that play a key role in the normal development of nerve cell networks.
“There’s still a lot we don’t know about how marijuana affects a baby’s rapidly developing brain,” said Mary E. O’Connor, MD, MPH, FAAP, a co-author of the clinical report and an executive committee member of the AAP Section on Breastfeeding. “But, based on what we know now, we’re advising women who are pregnant or nursing that the safest choice for their child is to avoid marijuana.”