Cannabis use rises among pregnant women despite potential fetal risks
Women report using marijuana for nausea, anxiety and sleep, but experts and medical societies warn there is no known safe level during pregnancy
Cannabis use among pregnant women is increasing, particularly in the first trimester, even as medical experts warn of potential harms to fetal development and newborn health.
A National Survey on Drug Use and Health published by the Substance Abuse and Mental Health Services Administration and other recent studies show a rising trend in marijuana and cannabidiol, or CBD, use during pregnancy. Researchers and clinicians say many women turn to cannabis to relieve pregnancy-related symptoms such as nausea, vomiting, insomnia, pain and anxiety. A University of Florida study found about one in six women reported using marijuana or a CBD product while pregnant, and roughly half of those users said they were not aware of the risks.
Marijuana contains two principal compounds: tetrahydrocannabinol, or THC, which produces psychoactive effects, and cannabidiol, or CBD, which does not. "CBD does not affect the brain or spinal cord, while THC brings on more of a euphoric 'high,'" said Dr. Alta DeRoo, chief medical officer of the Hazelden Betty Ford Foundation and a board-certified addiction specialist and obstetrician-gynecologist. Health experts note that the average THC content of cannabis products is substantially higher today than in past decades, and they say older research may not reflect the potency of contemporary products.
There is also limited clinical research on drug effects in pregnant people. A recent public health review found that fewer than 1 percent of drug trials in the past 15 years enrolled pregnant participants, a gap that complicates efforts to define safe exposure levels. National professional organizations including the American College of Obstetricians and Gynecologists, the American Society for Reproductive Medicine and the American Academy of Pediatrics advise against cannabis use during pregnancy or while attempting conception because of the limited safety data.
"Parents want to do the right thing for their health and especially for that of their future children," said Dr. Jamie Lo, an associate professor of obstetrics, gynecology and urology at Oregon Health & Science University, whose research focuses on cannabis and reproductive health. Lo said there is no known safe amount of cannabis for pregnant people and recommended seeking safer alternatives to treat symptoms or, for those who cannot abstain, reducing frequency of use.
After maternal use, active compounds in cannabis can cross the placenta and reach the fetus. DeRoo said fetal brain receptors for cannabinoids are present beginning near the third month of pregnancy. Studies in recent years have linked prenatal cannabis exposure to lower birth weight, smaller head circumference and higher rates of neonatal intensive care unit admission. A May review that analyzed 51 studies reported an association between prenatal marijuana use and an increased risk of preterm delivery and a 75 percent higher risk of low birth weight.
Medical societies and clinicians warn that smaller head size at birth has been associated with later neurological and developmental challenges. Smoking cannabis during pregnancy also introduces the risks associated with inhaled smoke, including reduced oxygen levels for the mother and fetus and possible respiratory problems. Any level of cannabis use can impair judgment, coordination and reaction time, raising the risk of falls and injuries during pregnancy, clinicians said.
Acute effects of excessive cannabis use can include red eyes, dry mouth, increased appetite, elevated heart rate, delayed reaction time and problems with concentration and memory. Some users experience anxiety or paranoia. Experts also caution about the potential for cannabis use disorder, defined as continued use despite negative consequences such as impaired relationships or failure to meet role obligations.
Clinicians report that some patients assume cannabis is safe during pregnancy because it is legal in many states or because it is a plant-derived product. Medical experts counter that legality and "natural" origin do not guarantee safety; for example, excessive intake of certain vitamins has known teratogenic effects. The limited trial data and changing potency of cannabis products complicate efforts to provide precise guidance on dose, frequency and timing that might be without risk.
Recent studies have also linked prenatal cannabis exposure with increased emergency department visits and hospitalizations for mothers, and some analyses suggest higher rates of complications related to elective surgery among cannabis users. Given the uncertainties and potential harms, clinicians advise pregnant people and those trying to conceive to discuss symptoms and treatment options with their health care providers and to consider established, safer therapies when available.
Public health officials say the trend underscores gaps in research and patient education. With use rising and safety data limited, experts recommend heightened counseling and more rigorous studies that include pregnant participants so clinicians can offer evidence-based guidance to those facing symptoms during pregnancy.