Characteristics of pregnant illicit drug users and associations between cannabis use and perinatal outcome in a population-based study

Background: According to the 2004 National Survey on Drug Use and Health, 4.6% of American women reported use of an illicit drug during pregnancy. Previous studies on illicit drug use during pregnancy and perinatal outcomes allowed inconsistent results. Methods: This population-based study included mothers who delivered live-born infants without birth defects between 1997 and 2004 and completed interviews for the National Birth Defects Prevention Study (response rate 69%; n=5871). Prevalence of self-reported illicit drug use (specifically cannabis, cocaine, and stimulants) during pregnancy and its associations with demographic and social factors were assessed. We used multivariable linear and logistic regression analyses to study the associations of cannabis use with birth weight and gestational age. Results: The prevalence of reported illicit drug use during pregnancy was 3.6% (standard error 0.24). Pregnant users of cannabis, cocaine, and stimulants were younger, had a lower level of education and lower household income, and were less likely to have used folic acid in the periconceptional period than nonusers. Illicit drug users were also more likely to have used alcohol and tobacco. After adjustment for confounding, cannabis use was not associated with mean birth weight or gestational age or with low birth weight or preterm delivery. Conclusion: Women who report use of illicit drugs during pregnancy differ in demographic and socioeconomic background from nonusers. Reported cannabis use does not seem to be associated with low birth weight or preterm birth. Published by Elsevier Ireland Ltd.