Prenatal tobacco and marijuana use among adolescents: Effects on offspring gestational age, growth, and morphology

Objective. This longitudinal study examined the effects of tobacco and marijuana use during pregnancy on the gestational age, growth, and morphology of 310 offspring of adolescents. Data were collected during 1990 through 1993. Methodology. The adolescents were drawn from a prenatal clinic in Pittsburgh, PA. They were interviewed at mid-pregnancy and at delivery to obtain information on tobacco, marijuana, and other substance use before and during pregnancy. Infants were examined 24 to 36 hours after birth. Results. The average maternal age was 16.1 (range 12 to 18 years); 70% were African- American. Prenatal tobacco use was associated with reduced birth weight, length, head and chest circumferences, and ponderal index, but not gestational age or the number of morphological abnormalities. Prenatal marijuana exposure was associated with reduced gestational age. Among whites, first trimester marijuana exposure was associated with an increased rate of minor physical anomalies. Prenatal marijuana exposure was not associated with any growth outcomes. Conclusions. These effects of prenatal tobacco and marijuana use were prominent despite lower levels of prenatal exposure in the offspring of adolescent mothers as compared with the offspring of adult mothers from the same clinic. Young maternal age may increase the offspring's risk of negative effects from prenatal tobacco and marijuana exposure.