Objective: To define the relationships between neonatal opiate withdrawal and drug-related factors such as maternal methadone dosage, maternal and neonatal plasma levels, and rate of decline of methadone in neonatal plasma.
Methods: Twenty-one methadone-dependent women and their newborn infants were studied. Fourteen of the women used other illicit drugs. The severity of neonatal withdrawal was assessed with a standardized scoring system. Venous blood samples for methadone levels were collected from the mothers within 24 hours of delivery and from their newborns within 24 hours of birth and on day 3-4 of life.
Results: The maternal methadone dosage at delivery correlated significantly with the maternal plasma level drawn at 16 hours postpartum (r = 0.512, P < .05), and the maternal methadone level in turn correlated significantly with the neonatal plasma methadone level on day 1 of life (r = 0.545, P < .05). A positive correlation was found between the severity of central nervous system signs of withdrawal and the rate of decline of the neonatal plasma methadone level from day 1 to day 4 of life (r = 0.550, P < .05).
Conclusion: This spectrum of relationships supports the concept that careful reduction of the maternal methadone dosage during pregnancy under intensive medical and psychosocial surveillance may benefit the drug-exposed new-born infant clinically.