THE IMPACT OF COCAINE AND MARIJUANA USE ON LOW-BIRTH-WEIGHT AND PRETERM BIRTH - A MULTICENTER STUDY

OBJECTIVE: Our aim was to evaluate prospectively the effects of cocain e and marijuana use on pregnancy outcomes. STUDY DESIGN: A prospective multicenter cohort study was conducted at seven university-based pren atal clinics in the United States from 1984 to 1989. The cohort descri bed herein consisted of a multiethnic population of 7470 pregnant wome n. Information on the use of drugs was obtained from personal intervie ws at entry to the study and assays of serum obtained during pregnancy . Pregnancy outcome data (low birth weight [< 2500 gm], preterm birth [< 37 weeks' gestation], and abruptio placentae) were obtained with a standardized study protocol. RESULTS: A total of 2.3% of the women use d cocaine and 11.0% used marijuana during pregnancy. Cocaine use was n ot associated with having a low-birth-weight infant (adjusted odds rat io 0.7, 95% confidence interval 0.4 to 1.3) or a preterm birth (1.3, 0 .9 to 2.0). There was no association between short-term exposure to co caine and preterm delivery (1.1, 0.3 to 4.0). However, cocaine use was strongly associated with abruptio placentae (adjusted odds ratio 4.2, 1.9 to 9.5). Marijuana use was not associated with low birth weight ( 1.1, 0.9 to 1.5), preterm delivery (1.1, 0.8 to 1.3) or abruptio place ntae (1.3, 0.6 to 2.8). By comparison, 35% of the women smoked cigaret tes during pregnancy, and cigarette smoking was positively associated with low birth weight (1.5, 1.2 to 1.8). CONCLUSIONS: In this populati on of women receiving prenatal care, cocaine use was uncommon and was not related to most adverse birth outcomes. Marijuana use was relative ly common and was not related to adverse pregnancy outcomes. Tobacco i s still the most commonly abused drug during pregnancy, 15% of all cas es of low birth weight in this study could have been prevented if wome n did not smoke cigarettes during pregnancy.