The Maternal Lifestyle Study (MLS)
Prenatal substance abuse continues to be a major public health problem
affecting millions of children in addition to placing both financial and
social burdens on society.
The Maternal Lifestyle Study (MLS) began as an interagency longitudinal
study in the early 1990’s specifically against the backdrop of debate and
controversy around the effects of prenatal cocaine exposure on child
outcomes. Accessing a large multi-site population of newborn infants and
their mothers through the NICHD Neonatal Research Network (NRN) allowed an
in-depth prospective study of mothers and children exposed in utero to
cocaine. The collaborative nature of the NRN also provided access to a
multi-cultural, multi-ethnic, socio-demographically varied population in
whom widespread use of drugs was previously demonstrated.
Now in its 13th year, the MLS is the largest clinical prospective
longitudinal study to date of prenatal drug exposure and child outcome.
Conducted at four Neonatal Research Network sites (University of Miami,
University of Tennessee at Memphis, Wayne State University, and Brown
University), the cohort includes 658 exposed and 730 comparison mother/child
In the first phase of the study, 19,079 pregnant mothers were recruited just before
or after they gave birth. Of these, 16,988 (89%) met basic eligibility criteria and
11,811 (70%) of these agreed to participate in the study. Drug use was confirmed by
mother interview and gas chromatography/mass spectroscopy (gc/ms) for cocaine/opiate
metabolites in the meconium of the infant. Based on this information, there were 1185
(10%) infants who were exposed to either cocaine or opiates during pregnancy. A total
of 7442 (63%) of the infants were confirmed to have been exposed to neither cocaine
nor opiates. There were 3184 (27%) infants whose exposure status was not confirmed.
The use of alcohol, tobacco, marijuana by the mother occurred in all three of these
Phase II of the study tracked the development of infants who had been exposed to
illicit drugs, comparing the results to infants whose mothers had not used illicit
drugs. A total of 1,388 subjects were recruited into this part of the study. Of
these, 658 were infants exposed to either cocaine, opiates or both. There were 730
infants who had been exposed to neither. All of these infants were seen at 1 month
of age. Their mothers or caretakers were encouraged to participate in visits at 4,
8, 10, 12, 18, 24, 30, and 36 months of age. At these visits, the children
participated in a variety of assessments that noted both their medical and
developmental outcomes over time. Mothers and caretakers were also asked questions
about the infant and the environment.
Mother/child dyads have continued their involvement in the study through
subsequent phases. Phase 3 covered visits of the child from the time he or she was
4 years, up until age 7. In Phase 4 children were seen between the ages of 8 and 11
at yearly clinic visits in addition to intermittent home and school visits. This
pattern of clinic, home and school visits continues into Phase V including children
between the ages of 12 and 15.
The MLS continues to study the effects of prenatal cocaine/opiate exposure
on immediate child outcomes that start in infancy (e.g. attention, relationship
to parent, neuromotor, physiologic reactivity, arousal/regulation, and medical
status) as well as latent effects on domains of function that become salient
as children reach school age (e.g. cognition, antisocial behavior, substance
use onset, psychopathology, neuroendocrine function, and health disorders).
This line of research also includes determining the effects of heavy cocaine
exposure and controlling for exposure to other drugs (alcohol, marijuana, and
tobacco), medical (e.g. physical growth) and environmental factors, gender,
minority status, and site.
In addition, the MLS studies how immediate and latent teratogenic drug effect
and the effect of postnatal caregiving environment including sociodemographics,
caregiving context and caregiver characteristics, combine to influence child
outcome. This includes specific aspects of the caregiving environment unique
to the drug culture and the role of protective factors. It also includes the
study of multiple pathways to latent outcome effects. For example, prenatal
exposure may result in behavior and executive function problems that in turn
lead to deviance and early onset of substance abuse.
It is now well documented that scientific reports in the 1980's were
exaggerated and incorrect in their portrayal of children exposed to
cocaine in utero as irreparably damaged. Current research does, however,
suggest that the effects of cocaine on child development are inconsistent,
subtle and need to be understood in the context of polydrug use and the
As a major longitudinal study, the MLS offers important scientific
contributions to the field of developmental research for both normal and
at-risk children. In addition, understanding the consequences of prenatal
cocaine exposure and its relationship with risky environments provides a
crucial framework for making treatment decisions and informing overall