Incidence of Postpartum Depression in Low-income Cannabis Users with and Without a History of Depression

While past research has linked cannabis use in pregnancy with a history of depression, sparse literature exists on cannabis use during pregnancy and postpartum depression (PPD). In this study, we aimed to better understand the association between PPD and cannabis use during pregnancy in those with and without a history of depression. This was a retrospective cohort study of patients who received prenatal care at a single institution between January 2017 and December 2019. Patient demographics, obstetric history, depression history, substance use history, and Edinburgh Postnatal Depression Scale (EPDS) scores were extracted from patients' medical records. Modified Poisson Regression with robust standard errors was used to estimate the relative risk (RR) of screening positive for PPD, adjusting for age at delivery, race/ethnicity, insurance type, marital status, and smoking history. Among the 799 subjects meeting inclusion criteria, 15.9% used cannabis during pregnancy. There was an increased risk of screening positive for PPD among prenatal cannabis users compared to non-users (aRR = 1.60, 95% CI: (1.05, 2.45)). Among individuals with a history of depression, the adjusted relative risk of screening positive for symptoms of PPD at the postpartum visit was 1.62 times greater in cannabis users compared to non-users (95% CI: (1.02, 2.58)). Prenatal cannabis use is associated with screening positive for PPD, particularly in those individuals with a history of depression. These results should discourage women with depression from self-medicating with cannabis in pregnancy and provide additional support to the existing recommendations to abstain from prenatal cannabis use.