Are infants exposed to methadone in utero at an increased risk for mortality?

Background The prevalence of opioid abuse is increasing in North America. Opioid abuse during pregnancy can cause medical, obstetric and psychosocial complications. Neonates exposed to opioids in utero often develop the neonatal abstinence syndrome. Methadone maintenance therapy is the treatment of choice for maternal opioid dependency. There have been unsupported concerns that infants cared for by mothers treated with methadone have higher mortality rates during the first year of life than in the general population. Objectives To compare the mortality rates of infants exposed to methadone in utero to those of general population in Ontario, Canada. Methods We utilized several provincial and national databases including those of the Office of the Chief Coroner of Ontario, the Canadian Institute for Health Information, and the Ontario Infant Mortality Rate Report. Reference organ weights were obtained from the peer reviewed literature. Results The Office of the Chief Coroner of Ontario has reported 8 deaths in children under one associated with in utero methadone exposure between January 1, 2006 and December 31, 2010. Over the same period there have been a total of 1103 cases of neonatal abstinence syndrome recorded in the province. The mean infant mortality rate in Ontario for children under the age of 1year over the same period was 5.2 per 1000 live births. The odds ratio for mortality among children with neonatal abstinence syndrome was not different from that in the general population [OR 1.45 (95% confidence interval 0.471-4.459)] (p=0.56). Conclusion The available data do not support the concerns that children under the age of one year, born to mothers on methadone maintenance therapy (MMT) are at an increased risk for mortality.