Buprenorphine reduces odds of neonatal abstinence syndrome
Children of mothers treated with buprenorphine for opioid dependency during pregnancy have a significantly higher birthweight, longer gestation period and a lower risk of neonatal abstinence syndrome, compared with the children of mothers treated with methadone.
The study compared the outcomes of 47 consecutive, prospectively followed pregnancies in mothers on opioid substitution therapy using buprenorphine with the outcomes of a retrospective control group of 35 consecutive cases of methadone-exposed pregnancies at the same hospital.
The only significant difference between the groups at baseline was that mothers prescribed buprenorphine were significantly younger. Smoking was prevalent and the majority of mothers in both groups were HCV positive. Two mothers in the buprenorphine group and three in the methadone group were HIV positive.
Combined prenatal, neonatal and early infant mortality was similar in both groups. Two intrauterine deaths occurred, both in the buprenorphine group, and two infants died of sudden infant death syndrome, both in the methadone group.
Children born to mothers on methadone substitution therapy had significantly lower birthweights than those born to mothers prescribed buprenorphine (P=0.008) and had a shorter gestational time (mean 38.6 weeks compared with 39.5 weeks, P=0.06). They also had almost twice the risk of neonatal abstinence syndrome (P=0.0008) and more than three times the risk of severe neonatal abstinence syndrome, defined as requiring pharmacological treatment, compared with those in the buprenorphine group (P=0.0004). The average length of stay in hospital was also longer for those in the methadone group.
Mothers in the buprenorphine group who started treatment before conception had better pregnancy outcomes than those who started treatment after presentation for antenatal care.
Opioid substitution therapy during pregnancy is based on the premise that the continued use of illicit drugs and its associated lifestyle represent the greatest threats to the wellbeing of both the mother and the child. Methadone is currently the treatment of choice in the UK for the management of opioid dependence in pregnancy, and buprenorphine is not licensed for this indication.
This study presents evidence that buprenorphine may offer advantages over methadone when treating pregnant women with opioid dependence.
Kakko J, Heilig M, Sarman I. Buprenorphine and methadone treatment of opiate dependence during pregnancy: Comparison of fetal growth and neonatal outcomes in two consecutive case series. Drug Alcohol Depend 2008;96:69-78Reviewer
Dr Jez Thompson
Former GP, Clinical Director, Leeds Community Drug Services