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Marijuana Use in Pregnancy and While Breastfeeding

Metz, Torri D., MD, MS; Borgelt, Laura M., PharmD

doi: 10.1097/AOG.0000000000002878
Contents: Substance Use Disorder: Clinical Expert Series
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The prevalence and perceived safety of marijuana use in pregnancy are increasing with expanding legalization. Marijuana crosses the placenta and passes into breast milk, resulting in fetal and neonatal exposure. Many women cite medical reasons for prenatal marijuana use such as nausea and vomiting of pregnancy, anxiety, and chronic pain. The scientific literature regarding marijuana in pregnancy is mixed, resulting in confusion among practitioners as to how to counsel women about risks of use. In addition, there is a paucity of literature related to marijuana use and breastfeeding. Existing pregnancy studies are predominantly retrospective cohorts with a reliance on self-report for ascertainment of exposure, which underestimates use. Many studies fail to adjust for important confounding factors such as tobacco use and sociodemographic differences. Despite the limitations of the existing evidence, there are animal and human data suggesting potential harm of cannabis use. The harms are biologically plausible given the role of the endocannabinoid system in pregnancy implantation, placentation, and fetal neurologic development. Two recent systematic reviews and meta-analyses found an association between marijuana use and adverse perinatal outcomes, especially with heavy marijuana use. In addition, three longitudinal cohort studies demonstrate a possible effect of prenatal marijuana exposure on long-term neurobehavioral outcomes. Marijuana use may be associated with growth restriction, stillbirth, spontaneous preterm birth, and neonatal intensive care unit admission. Therefore, women should be advised to refrain from using marijuana during pregnancy and lactation.

Based on available animal and human data demonstrating the potential for maternal and fetal harm, pregnant and breastfeeding women should refrain from using marijuana.

Denver Health and Hospital Authority, Denver, and the University of Colorado School of Medicine and the University of Colorado Skaggs School of Pharmacy, Aurora, Colorado.

Corresponding author: Torri D. Metz, MD, MS, 30 North 1900 East, 2B200, Salt Lake City, UT 84132; email:

Dr. Metz was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development under award number 5K12HD001271-18. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Financial Disclosure Dr. Borgelt received grant funding from the Colorado Department of Public Health and Environment (CDPHE) for a study evaluating the use of cannabidiol for the treatment of refractory pediatric epilepsy. Additionally, she has provided continuing education for pharmacists through PharmCon, Inc and served on seven different working groups for the Colorado Department of Revenue and CDPHE regarding use of cannabis and patient safety. Dr. Metz did not report any potential conflicts of interest.

Continuing medical education for this article is available at

The authors thank Amanda Allshouse for creating Figure 3. Ms. Allshouse is supported by the Department of Obstetrics and Gynecology at Denver Health and Hospital Authority.

Each author has indicated that she has met the journal's requirements for authorship.

Received February 28, 2018

Received in revised form April 04, 2018

Accepted May 03, 2018

© 2018 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.