USE OF BUPRENORPHINE IN PREGNANCY

Buprenorphine is a semi-synthetic opioid derived from the morphine alkaloid thebaine which has mixed agonist-antagonist properties. It is typically administered intramuscularly, intravenously, by sublingual tablet, or via transdermal patch. Buprenorphine is used for the treatment of moderate-to-severe pain and, when combined with psychological treatment, as a substitution treatment in the management of opioid dependence.

Acute opioid withdrawal during pregnancy carries a risk of fetal death. Opioid substitution therapy is recommended in pregnancy as it carries a lower risk to the fetus than continued use of illicit drugs. Where a woman is stabilised on buprenorphine for treatment of opioid dependence, therapy should be continued in pregnancy.

The limited available data relating to use of buprenorphine during human pregnancy have not identified increased risks of congenital malformation, preterm delivery, or low infant birth weight. However, studies have generally assessed the risk of these outcomes in comparison with cohorts exposed to other opioid substitution therapies, which means that data are lacking about the risk of adverse pregnancy outcomes in comparison with the general population. This also limits the conclusions that can be provided about use of buprenorphine as an analgesic. Data on rates of intrauterine death, miscarriage and adverse neurodevelopment following buprenorphine exposure do not currently raise concern but are too limited to state definitively that no increased risk exists.

Use of any opioid during pregnancy, particularly around the time of delivery, confers a risk of neonatal respiratory depression. Prolonged use of opioids throughout pregnancy may result in neonatal withdrawal and this has been documented specifically in buprenorphine-exposed infants. Therefore, infants exposed to buprenorphine in utero should ideally be delivered in a unit with facilities to provide monitoring and treatment for these conditions.

Where buprenorphine overdose occurs in pregnancy, maternal toxicity is likely to be a major factor in determining risk to the fetus. If use of an antidote (e.g., naloxone) is required in the management of maternal toxicity, it should not be withheld on account of pregnancy.

Exposure to buprenorphine at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy. Additional fetal monitoring may be required in pregnancies complicated by severe pain or opioid addiction on a case-by-case basis. Other risk factors may also be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.