Illicit drug use and adverse birth outcomes: Is it drugs or context?

Illicit drug use has been associated with adverse birth outcomes in many studies. None, however, have controlled for the full array of social, psychosocial, behavioral, and biomedical risk factors that are related to both drug use and birth outcomes. This study examined the degree to which adverse birth outcomes associated with drug use are due to the drugs versus surrounding factors. The sample included 808 low-income women who delivered a singleton, live birth at Johns Hopkins Hospital between 1995 and 1996. Use of marijuana, cocaine, and opiates was determined by self-report, the medical record, and urine toxicology screens at delivery. Information on various sociodemographic, psychosocial, behavioral, and biomedical risk factors was gathered from a postpartum interview and medical records. Multivariable regression models of birth outcomes (mean birth weight and low birth weight, LBW <2500g) were used to assess the effect of drug use independent of associated factors. In unadjusted results, cocaine and opiate use were related to mean birth weight (-329 and -239 grams, p<0.01) and LBW (ORs: 1.93 and 2.06, p<0.05). After adjusting for all associated factors, only the effect of cocaine on mean birth weight remained significant (-143 grams, p=0.04); neither drug was significantly related to LBW (ORs: 1.16 and 1.69). Most of the unadjusted effects of drug use were explained by associated psychosocial and behavioral factors, particularly stress, smoking, and lack of early prenatal care. Thus, prevention efforts that aim to improve newborn health must also address the surrounding context in which drug use frequently occurs.