PROVIDENCE, R.I. -- Newborns whose mothers used methamphetamine during pregnancy are 3.5 times more likely to be born underweight compared to newborns whose mothers didn't use the drug, according to a research study led Brown Medical School Professor Barry Lester.
The study, published in Pediatrics, is the first large-scale investigation of the prenatal effects of methamphetamine, a popular and highly addictive stimulant. It is also the first prospective study: these infants will be followed over time.
Results show that newborns exposed to the drug were not born too soon – they were born too small. Methamphetamine appears to restrict the nutrient-rich flow of blood into the placenta, increasing the risk that the newborn will be "small for gestational age" – born full-term but below the 10th percentile for weight. Growth-restricted newborns in the study weighed less than 5 pounds.
The long-term effects of growth restriction can be serious. These children are more likely to develop type 2 diabetes and metabolic syndrome, a collection of heart attack risk factors such as high blood pressure and obesity.
"We're also very concerned about the developmental implications," said Lester, a professor of pediatrics and psychiatry and human behavior and director of the Brown Center for the Study of Children at Risk, which was established with Women & Infants Hospital in Providence. "Children who are born underweight tend to have behavior problems, such as hyperactivity or short attention span, as well as learning difficulties."
Researchers enrolled 1,618 patients in the study from four medical centers, located in Tulsa, Okla., Des Moines, Iowa, Los Angeles and Honolulu. Women were asked if they had used methamphetamine, but researchers also checked for evidence. Meconium, a newborn's first few stools and also a buildup of material gained during pregnancy, was scraped from diapers and chemically screened for the presence of the drug.
Results showed that 1,534 newborns were unexposed to methamphetamine in utero. Another 84 newborns were exposed – and were more than 3 times as likely to be born too small. Researchers arrived at that figure even after adjusting for other factors that may contribute to growth restriction, such as socioeconomic status and other substance use, including tobacco and alcohol.
Lester has studied the effects of drug use on infants and children for more than 20 years. He oversees the Maternal Lifestyle Study, the nation's largest prospective study of cocaine-exposed children. About 1,400 newborns were enrolled in Providence, Detroit, Memphis and Miami. Those children are now turning 13, and researchers continue to study how prenatal cocaine exposure, by itself and in combination with other drug and environmental factors, affects their cognitive, psychological, behavioral and emotional outcomes as well as their school performance.
Lester said initial results from the methamphetamine study, called the Infant Developmental Environment and Lifestyle Study (IDEAL), mirror early results from the Maternal Lifestyle Study. In that study, researchers also found that cocaine-exposed newborns were more likely to be born small for gestational age.
"Both of these drugs are central nervous stimulants, and it appears that both drugs have similar effects on the developing fetus," he said. "But I hope that the 'crack baby' hysteria does not get repeated. While these children may have some serious health and developmental challenges, there is no automatic need to label them as damaged and remove them from their biological mothers. There are alternatives for the mother and the baby that can keep families together, such as the specialized drug court we established here in Providence that is based on treatment, rather than punishment."
The research team will follow infants in IDEAL until the infants are 3 years old. With additional funding, the team will follow them for even longer.
Lynne Smith, M.D., a researcher with the Los Angeles Biomedical Institute at Harbor-UCLA Medical Center and the David Geffen School of Medicine at UCLA, is the lead author of the Pediatrics article. Linda LaGasse, Sheri Della Grotta and Jing Liu of the Brown Center for the Study of Children at Risk are also authors. Others include Chris Derauf, M.D., and William Haning, M.D., University of Hawaii; Penny Grant, M.D., University of Oklahoma; Amelia Arria, University of Maryland; Marilyn Huestis, National Institute on Drug Abuse; Arthur Strauss, M.D., Long Beach Memorial Medical Center.
The National Institute on Drug Abuse and the National Center for Research Resources funded the work.
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