Objectives Substance use during pregnancy is a significant public health issue. Prenatal substance use increased in the past decade while prenatal cigarette smoking has remained stable. Co-use of tobacco and other drugs is a concern because of potential additive risks. This study aims to describe the prevalence rates of substance use among pregnant women and examine the association between smoking status (nonsmoker, recent quitter and current smoker) and other drug use. Methods In this cross-sectional study, pregnant women (n = 500) were recruited from two obstetric practices to complete three substance use screeners and have their urine tested for 12 different drug classes, including cannabis, opioids and cocaine. Participants were divided into three groups based on survey responses: nonsmokers, recent quitters (smoked in the month prior to pregnancy but not past month) and current smokers (past-month). Results Approximately 29% of participants reported smoking in the month before pregnancy. During pregnancy, 17, 12 and 71% were current smokers, recent quitters and nonsmokers respectively. Overall prevalence of illicit or prescription drug use in pregnancy was 27%. Cannabis was the most common drug used in pregnancy with prevalence of 22%, followed by opioids (4%), cocaine (1%), tricyclic antidepressants (TCAs) (1%), amphetamines (1%), and benzodiazepines (1%). On multivariable logistic regression, smoking in pregnancy was associated with a positive urine drug screen; with adjusted odds ratio (aOR) 4.7 (95% CI 2.6-8.3) for current smokers and 1.6 (95% CI 0.8-3.3) for recent quitters. Factors negatively associated with positive drug screen were second and third trimester pregnancies, 0.5 (0.3-0.9) and 0.3 (0.2-0.6) respectively; and employment, 0.5 (0.3-0.8). Conclusions for Practice Co-use of tobacco and illicit drugs, particularly cannabis, is relatively high during pregnancy. Additional research is needed to understand the health implications of co-use versus use of tobacco only. Given the strong association between smoking and other drug use, clinicians should routinely assess for illicit drug use in women who smoke during pregnancy.
