A NIDA-funded study found that newborns whose mothers abused methamphetamine during pregnancy showed higher rates of growth restriction compared with unexposed newborns. Dr. Barry M. Lester and colleagues at Brown Medical School and other institutions analyzed data from 1,618 mother-infant pairs, 84 of whom were meth-exposed. The meth-exposed newborns weighed 3,174 grams (7 pounds), on average, versus 3,381 grams (nearly 7.5 pounds) for unexposed newborns. The meth-exposed newborns also had a lower gestational age at birth (38.7 weeks versus 39.2 weeks). Although most infants were full term, methamphetamine infants were 3.5 times as likely to be small for gestational age—a finding that suggests fetal growth restriction.
In a followup with 166 infants from the study, the researchers assessed the newborns' behavioral capabilities within the first 5 days of life. The 74 meth-exposed newborns showed greater lethargy and were more difficult to awaken than the 92 unexposed newborns. Once aroused, however, meth-exposed newborns also showed a sign of physiological distress—difficulty maintaining normal, regular breathing. The differences held when the researchers took into account factors known to affect fetal growth, including maternal smoking and other drug abuse and socioeconomic status. In addition, higher concentrations of methamphetamine in samples of the babies' stool were related to increased central nervous system stress.