Use of Cannabis and use of tobacco overlap, and co-use of Cannabis and tobacco has increased over the past decade among adults. The current study aims to document the prevalence and correlates of co-use of Cannabis and tobacco cigarettes among adult pregnant women utilizing secondary data from a larger study that compared and validated screeners for illicit and prescription drug use during pregnancy. Pregnant women (N = 500; 71% African American; 65% never married, average age of 28 years) were recruited from two urban University obstetric clinics between January and December 2017. Participants self-reported demographic, Cannabis, and tobacco cigarette use characteristics, and provided urine and hair samples for drug testing. Within two weeks after due date, research staff reviewed participants' electronic medical records to collect birth outcome data. Results showed that 9.0% reported co-use of Cannabis and tobacco, 12.1% reported Cannabis only use, 7.8% reported tobacco cigarette only use, and 71.1% reported no Cannabis or tobacco cigarette use in the past month. The birth outcomes to emerge as significant correlates of co-use of Cannabis and tobacco cigarettes were small head circumference, and the occurrence of birth defects, with the co-use group having the highest odds of a small head circumference [aOR: 5.7 (1.1-28.9)] and birth defects [aOR: 3.1 (1.2-8.3)] compared with other use groups. The Cannabis only group had 12 times higher odds of a stillbirth or miscarriage (aOR = 12.1). Screening and interventions to address concurrent Cannabis and tobacco use during pregnancy are needed, particularly among subpopulations with higher co-use rates. It is imperative to further explore and highlight the possible health implications of maternal co-use given the high prevalence rates found in this study sample.
