Relationship between maternal methadone dose at delivery and neonatal abstinence syndrome.

OBJECTIVE

To estimate the relationship between maternal methadone dose and the incidence of neonatal abstinence syndrome (NAS).

STUDY DESIGN

We performed a retrospective cohort study of pregnant women treated with methadone for opiate addiction who delivered live-born neonates between 1996 and 2006. Four dose groups, on the basis of total daily methadone dose, were compared (<or=80 mg/d, 81-120 mg/d, 121-160 mg/d, and >160 mg/d). The primary outcome was treatment for NAS. Symptoms of NAS were objectively measured with the Finnegan scoring system, and treatment was initiated for a score>24 during the prior 24 hours.

RESULTS

A total of 330 women treated with methadone and their 388 offspring were included. Average methadone dose at delivery was 117+/-50 mg/d (range, 20-340 mg/d). Overall, 68% of infants were treated for NAS. Of infants exposed to methadone doses<or=80 mg/d, 81-120 mg/d, 121-160 mg/d, and >160 mg/d, treatment for NAS was initiated for 68%, 63%, 70%, and 73% of neonates, respectively (P=.48). The rate of maternal illicit opiate abuse at delivery was 26%, 28%, 19%, and 11%, respectively (P=.04).

CONCLUSION

No correlation was found between maternal methadone dose and rate of NAS. However, higher doses of methadone were associated with decreased illicit opiate abuse at delivery.