Prescribers should consider the risks of addiction and neonatal opioid withdrawal before starting opioid pain relief, particularly in women of childbearing age, say researchers writing in CMAJ Open
(online, 11 February 2015).
The call follows their study into the number of babies born with neonatal abstinence syndrome in Ontario, Canada, between 1992 and 2011, which analysed the pattern of opioid prescribing to their mothers before and during pregnancy.
The incidence of newborn opioid withdrawal or neonatal abstinence syndrome went up from 0.28 per 1,000 live births in 1992 to 4.29 per 1,000 live births in 2011, a 15-fold rise in 20 years.
During the final five years of the study, 1,901 newborns were diagnosed with the syndrome. Some 930 of them were born to mothers whose prescription drugs were paid for by the state.
Of that group of women, 67% received an opioid prescription in the one to two years before their baby was born, 81% in the year to 100 days before delivery and 70% in the 100 days before delivery.
The proportion of women receiving prescriptions for methadone increased as they approached delivery, while prescriptions for other opioids went down. This trend, according to the researchers, suggests that opioid dependence during pregnancy was often recognised and appropriately treated.
The researchers point out that in Ontario addiction to prescription opioids has now overtaken heroin addiction as the most common reason to start methadone treatment.
“This observation raises the possibility that most of the pregnant women receiving methadone in our study had prescription opioid dependence,” they say. “Collectively, these observations suggest that the prescribing of opioids for chronic pain is a risk factor for addiction and the subsequent need for methadone treatment during pregnancy, leading to infants born with neonatal opioid withdrawal.”