Obstetric and neonatal outcomes associated with maternal naltrexone exposure

Poor maternal and neonatal outcomes are associated with the pregnant heroin user. These include increased antepartum haemorrhage, decreased neonatal birthweight and increased neonatal mortality. Medically supervised withdrawal from heroin during pregnancy has, however, been discouraged due to possible risk to the fetus and because of the high incidence of return to regular illicit heroin use by the mother. In recent years, however, a number of withdrawal procedures using anaesthesia, oral sedation, or intravenous sedation, precipitated by naloxone and/or naltrexone have been developed and carried out successfully on pregnant heroin users. We have now collated information on 18 cases (19 detoxifications) from three countries (Portugal, Australia and the United Kingdom). These case study data, although limited, indicate that detoxification of the pregnant heroin user is possible without significant risk to the neonate or mother, with many women not returning to dependent heroin use following detoxification. Naltrexone maintenance has also been used in the non-pregnant heroin user to discourage illicit heroin use. Similarly to methadone, stabilisation on naltrexone may be associated with conception and pregnancy Over the past three years, 26 women have conceived while on the Western Australia naltrexone program. Due to the unknown teratogenic effects, most have ceased naltrexone intake at approximately seven or eight weeks gestation. In a number of instances, however, naltrexone maintenance has been recommenced following return to a dependent pattern of heroin use. As a consequence, neonates have had different periods of naltrexone exposure, building from the initial seven or eight weeks. We now report on seven women who have delivered and three who are well into their third trimester. Neonatal and obstetric features were unremarkable with good Apgar scores, birthweight and head circumference observed. In the three cases still in third-term gestation, normal fetal development has been observed at recent ultrasound examinations. These case data indicate that naltrexone maintenance may have a role in the management of the pregnant heroin user.