Methods: Data from the Marijuana Supplemental Questionnaire of the 2017-2020 Phase 8 Pregnancy Risk Assessment Monitoring System were used to identify the association between cannabis use during pregnancy and breastfeeding initiation and duration.

Results: Overall, 7% of participants reported prenatal cannabis use; among these individuals, 76% initiated breastfeeding compared to 94% of those abstaining during pregnancy and 88% who never used cannabis. Among individuals who initiated breastfeeding, those who used cannabis prenatally breastfed for a shorter duration (7.6 weeks; SD=0.4) than those who abstained (11.4 weeks, SD=0.5) or never used (11.3 weeks, SD=0.1).

Conclusion: Breastfeeding postpartum is not recommended among perinatal individuals using cannabis, yet a majority of those who used cannabis during pregnancy did initiate breastfeeding. Those who abstain are different in their breastfeeding behavior compared to prenatal cannabis users and never users. Breastfeeding cessation is occurring earlier for those who are using cannabis during pregnancy. Given the potentially harmful effects of cannabis use on fetal development, more research is needed to clarify health outcomes and improve public health messaging to obstetric providers and patients.