Context: Maternal use of cocaine during pregnancy remains a significant public health problem, particularly in urban areas of the United States and among women of low socioeconomic status. Few longitudinal studies have examined cocaine-exposed infants, however, and findings are contradictory because of methodologic limitations.
Objective: To assess the effects of prenatal cocaine exposure on child developmental outcomes.
Design: Longitudinal, prospective, masked, comparison birth cohort study with recruitment in 1994-1996.
Setting: Obstetric unit of a large US urban teaching hospital.
Participants: Four hundred fifteen consecutively enrolled infants (218 cocaine-exposed and 197 unexposed) identified from a high-risk, low-socioeconomic status, primarily black (80%) population screened through clinical interview and urine and meconium samples for drug use. The retention rate was 94% at 2 years of age.
Main outcome measures: The Bayley Mental and Motor Scales of Infant Development, assessed at 6.5, 12, and 24 months of corrected age.
Results: Controlled for confounding variables, cocaine exposure had significant effects on cognitive development, accounting for a 6-point deficit in Bayley Mental and Motor Scales of Infant Development scores at 2 years, with cocaine-exposed children twice as likely to have significant delay (mental development index <80) (odds ratio, 1.98; 95% confidence interval, 1.21-3.24; P =.006). For motor outcomes, there were no significant cocaine effects.
Conclusions: Cocaine-exposed children had significant cognitive deficits and a doubling of the rate of developmental delay during the first 2 years of life. Because 2-year outcomes are predictive of later cognitive outcomes, it is possible that these children will continue to have learning difficulties at school age.