Cannabis and Alcohol in Pregnancy

If you’re pregnant, don’t drink any alcohol. Avoiding alcohol during pregnancy is a core message from the Centers for Disease Control (CDC) and the American College of Obstetricians and Gynecologists (ACOG). No amount, timing, or type of alcohol is safe in pregnancy, and abstinence is always best.

Cannabis use during pregnancy is also risky. However, for pregnant women with opioid use disorder (OUD), the CDC and National Institute for Drug Abuse (NIDA) recommend medication with methadone or buprenorphine and therapy. Medication for opioid use disorder (MOUD) leads to better outcomes for mother and baby. Starting MOUD early in pregnancy is crucial.

Despite clear admonitions to avoid alcohol in pregnancy, U.S. surveillance data from large national surveys consistently demonstrate that alcohol use during pregnancy is common. CDC analyses of the National S urvey on Drug Use and Health (NSDUH) and related data show that 13% to14% of pregnant women had current alcohol use (during the past 30 days), and about 5% reported binge drinking. The figures represent hundreds of thousands of pregnancies annually with alcohol exposure.

Of those engaged in current drinking, 17.8% didn’t have a current health care provider. The women may not have realized until recently that they were pregnant, since many pregnancies are unplanned. The researchers also found that 27.4% of current drinkers who were pregnant suffered frequent mental stress.

Alcohol quickly crosses the placenta, but the fetus has limited capacity to metabolize it, resulting in prolonged exposure during critical periods of growth and brain development. The fetal central nervous system is particularly vulnerable to alcohol. Neurodevelopmental harm may occur even in the absence of facial or growth abnormalities in the newborn.

Alcohol causes a spectrum of lifelong conditions collectively referred to as fetal alcohol spectrum disorders (FASD). They include growth restriction, characteristic craniofacial features, structural anomalies, and—most consistently—neurodevelopmental impairment affecting cognition, executive function, attention, behavior, and adaptive functioning. Many affected individuals don’t exhibit classic facial features, contributing to under-recognition of the disorder. FASD is entirely preventable by the avoidance of alcohol during pregnancy.

Higher levels of exposure, particularly binge drinking, are associated with increased risks of miscarriage, stillbirth, preterm birth, and other adverse outcomes. Vulnerability is modified by genetic factors, nutrition, and co-exposures to other substances.

The CDC and ACOG emphasize universal, nonjudgmental prenatal screening and brief intervention as part of routine prenatal care. Any alcohol use during pregnancy is classified as excessive. Because exposure is frequently under-reported—particularly early in pregnancy due to stigma or delayed pregnancy recognition—clinicians focus on prevention.

Cannabis in Pregnancy

Alcohol use during pregnancy is roughly twice as common as cannabis use. On a population level, this corresponds roughly to 485,000 pregnancies with recent alcohol use versus 244,000 with recent cannabis use annually in the U.S.

CDC data from eight states show that, in 2017, 4.2% self-reported marijuana use during pregnancy; more recent NSDUH estimates, covering 2021 to 2023, indicate a 6.8% prevalence, with higher use in the first trimester. Among pregnant women reporting current alcohol use, more than one-third reported using at least one other substance, usually tobacco or cannabis.

Prenatal cannabis use continues to increase, and cannabis remains the most commonly used illegal substance in pregnancy. Most experts suggest avoiding cannabis and THC-containing products during pregnancy and lactation. The recommendation is supported by consistent associations between prenatal cannabis exposure and adverse birth outcomes. New data also link cannabis use to pregnancy complications.

Multiple meta-analyses and population-based cohort studies report that prenatal cannabis use is associated with increased odds of low birth weight, small for gestational age (SGA) size, preterm birth, admission to a neonatal intensive care unit, and sometimes perinatal mortality. A recent study reported in JAMA Pediatrics examined infant outcomes—preterm birth (PTB, birth before 37 weeks of gestation), small for gestational age (SGA), low birth weight (LBW; weight less than 2,500 g), and perinatal mortality. Cannabis use in pregnancy was associated with greater odds of PTB, SGA, and LBW, even after adjusting for co-use of tobacco products.

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A very large study identified associations between prenatal cannabis use and gestational hypertension, preeclampsia, placental abruption, and altered gestational weight-gain patterns. Although causality cannot be assumed, the findings support framing risks within the maternal-placental-fetal unit.

Children of mothers using cannabis during pregnancy show higher rates of anxiety, aggression, and hyperactivity, as well as higher levels of the stress hormone cortisol, compared to children of non-cannabis users. Maternal cannabis use is also associated with a reduction in the high-frequency component of heart rate variability—the change in time interval between heartbeats—which normally reflects increased stress sensitivity.

In addition, genetic analyses of placental tissue collected at birth in some participants revealed that maternal cannabis use is associated with lower expression of key immune-activating genes, including pro-inflammatory cytokines protecting against dangerous germs. The analysis also predicted higher anxiety in children of mothers who use cannabis.

“Pregnant women are being bombarded with misinformation that cannabis is of no risk," says Yasmin Hurd, Ph.D., Ward-Coleman, chair of translational neuroscience, director of the Addiction Institute at Mount Sinai Medical Center, and senior author of the paper. “The reality is that cannabis is more potent today than even a few years ago. Our findings indicate that using it during pregnancy can have a long-term impact on children.”

The study results underscore the need for non-biased education and outreach to the public, particularly vulnerable populations of pregnant women, regarding the potential impact of cannabis use. Disseminating the data and accurate information is essential to improving the health of women and their children.”

Some meta-analyses report increased ADHD symptoms and autism spectrum disorder (ASD) among children of women using cannabis during pregnancy, while others find no increased risks for ASD and only modest elevation in ADHD risk.

Cannabis use during pregnancy frequently co-occurs with nicotine and alcohol use. Combined drug exposures amplify risks, with studies reporting higher rates of maternal morbidity, neonatal morbidity, and infant death among those exposed to cannabis and nicotine compared with exposure to either alone.

Research is ongoing . According to Dr. Dikea (Kay) Roussos-Ross, a researcher at the University of Florida College of Medicine who is board-a board-certified specialist in obstetrics and gynecology, psychiatry, and addiction medicine, marijuana- and/or cannabinoid-exposed pregnant women are willing to participate in long-term research studies with their babies if they can build a trusting relationship with the research staff and are confident of their anonymity

Avoiding cannabis is recommended during breastfeeding. Prospective studies demonstrate that THC and other cannabinoids are measurable in human milk, with concentrations remaining elevated with repeated use over a single day. More frequent use is associated with higher infant exposure. During the first months of life, infants normally have lower metabolism and kidney-clearance rates than adults do. This immaturity prevents infants from detoxifying and excreting chemicals, leading to higher levels of toxic substances.

Conclusion

Humans have used alcohol for millennia. Fermented beverages date back to around 7000 BCE in China, with records of distilled spirits in Egypt and Babylon dating to around 2000 BCE. But it was not until 1973 that Drs. Kenneth Jones and David Smith coined the term and formally described "Fetal Alcohol Syndrome", establishing the pattern of birth defects as a medical diagnosis. Data for cannabis and pregnancy is emerging as use increases.

It is best for themselves and their babies for pregnant women to avoid all alcohol and cannabis. The risks of cannabis use are not all known yet, but studies of alcohol and cannabis use will likely show continued or new risks to infant and mother of maternal use of the substances.