The Maternal Lifestyle Study (MLS)

Overview

This is a longitudinal, multi-site observational study of the long-term effects of a mother's use of cocaine and/or opiates during pregnancy on her infant. This observational study evaluates the medical, developmental, social, environmental, and neurobehavioral outcomes for 1,400 of the original cohort of children. A series of follow-up examinations of these children were conducted in 5 phases: 1-36 months, 3.5-7 years, and 8-11 years. Children are currently being examined at 13 years of age.

Interest in and availability of cocaine, marijuana, and opiates have complicated long-term investigations into the effects of the widespread recreational use of easily accessible substances like alcohol and tobacco. It remains impossible to determine in single site, small number studies what effects may be related to the use of a specific drug. By accessing the large multi-site population of newborn infants and their mothers available in the NICHD Neonatal Research Network, this study is evaluating the short- and long-term effects of mothers' cocaine and/or opiate use during pregnancy on their term or preterm infants. Maternal practices assessed in this study include the use and abuse of opiates, cocaine, alcohol, marijuana, and nicotine. This study will address acute perinatal events and long-term medical, developmental, social, environmental, and neurobehavioral outcomes of infants whose mothers engaged in these maternal practices. The study will determine whether specific acute and long-term effects can be attributed to the use and abuse of specific substances. Over 2 years, approximately 20,000 infants were screened with a goal of enrolling 16,000 infants. It was estimated that approximately 20% of infants would have been exposed to cocaine or opiates. The determination of exposure was based on self-report by the mother or positive meconium assay. The first phase of the study evaluated the acute effects of maternal practices on infants. This phase involved all mothers who agreed to respond to the initial questionnaire and who allowed the meconium drug screen to be performed on their infants. Acute outcomes are being compared between infants who were exposed to cocaine and opiates through their mothers' use (the exposed group) and infants who were not exposed (the nonexposed group). Acute outcomes include abruptio placenta, fetal growth retardation, non-life threatening congenital malformations, respiratory distress syndrome, chronic lung disease, periventricular-intraventricular hemorrhage, necrotizing enterocolitis, retinopathy of prematurity, and periventricular leukomalacia. The second phase of the study compared 1,400 exposed and nonexposed infants with respect to long-term neurodevelopmental outcomes. These infants were among the 16,000 infants enrolled in Phase I. It was estimated that 70% of the screened population would consent to participate in Phase II of the study, and 50% of these participants would complete all visits over the initial 3-year study period (2,000 exposed infants enrolled into Phase II and 1,000 exposed infants would complete all follow-up visits). For each exposed infant, an infant of similar age, race, sex, and either alcohol history or maternal age was selected from the nonexposed, screened population. All infants had physical, neurological, gestational age, and growth assessments at birth. The exposed and nonexposed infants were examined at 1, 4, 7, 9, 12, 18, 24, and 36 months corrected age. Follow-up assessments include medical history, and developmental, behavioral, social, and environmental outcomes. The third phase of the study compared children at ages 4 to 7. The fourth phase is now comparing outcomes in children ages 8 to 11 years old. Assessments include measures of cognition, school performance, antisocial behavior, onset of substance use, psychopathology, neuroendocrine function, and health disorders. Seventy-one percent of the original sample is still enrolled.