In a large cohort study of infants born to mothers prescribed methadone for opioid dependence, 45.5% needed pharmacological treatment for neonatal abstinence syndrome. The syndrome was more likely in the babies of women taking high-dose methadone, whereas those who were breastfed were less likely to need pharmacological treatment. ' Substitute prescribing of methadone to opioid-dependent women in pregnancy helps stabilise aspects of lifestyle, reduces some drug-related risks, and reduces the risk of pre-term birth and intrauterine growth retardation. Higher doses of methadone may be associated with less risky patterns of illicit drug use. However, they are also associated with a greater risk of neonatal abstinence syndrome. Pregnant drug-misusing women should be maintained on the lowest dose of methadone compatible with stability and supported to breastfeed their infants.'