Buprenorphine in pregnancy

• seek expert advice
• opioid misuse in pregnancy (1,2,3)
  • pregnant women who misuse opioids have an increased chance for pregnancy related problems
    • include poor growth of the baby, stillbirth, premature delivery, and the need for C-section
    • some women who misuse opioids also have unhealthy lifestyles that can result in health problems for both the mother and the baby
      • for example, poor diet choices can lead to mothers not having enough nutrients to support a healthy pregnancy and could increase the chance of miscarriage and premature birth; sharing needles to inject opioids increases the risk of getting diseases like hepatitis C and/or HIV which can also infect the baby
        
        
• opioid treatment in pregnancy
  • maintenance, at a dose that stops or minimises illicit use, is most appropriate for ensuring continuity of management of pregnancy and aftercare
  • methadone in pregnancy
    • many mothers request detoxification, although during the first trimester the patient should normally be stabilised as there is an increased risk of spontaneous abortion
    • detoxification in the second trimester may be undertaken in small frequent reductions - for example 2-3 mg methadone every 3-5 days - as long as illicit opiate use is not continuing
      • if illicit opiate use continues, strenuous efforts should be made to stabilise the patient on a prescribed opioid, which may involve increasing its dose
      • further detoxification should not generally be undertaken in the third trimester because there is evidence that maternal withdrawal, even if mild, is associated with fetal stress, fetal distress, and even stillbirth. However, for some, slow, carefully monitored reductions may safely be continued as long as there are no obstetric complications or resumption of illicit drug misuse
    • metabolism of methadone is increased in the third trimester of pregnancy and it may occasionally be necessary to increase the dose or split it, from once-daily consumption to twice-daily consumption, or both
    • methadone has been used safely for many years but buprenorphine is not licensed for use with pregnant women
      
      
  • buprenorphine (4)
    • is a semi-synthetic opioid that only partially activates opiate receptors
    • use of buprenorphine at any stage in pregnancy would not usually be considered as medical grounds for termination of pregnancy
    • pregnancies complicated by severe pain may require additional fetal monitoring, this should be assessed on a case-by-case basis
    • if clinically indicated, buprenorphine should be used at the lowest effective dose for the shortest possible duration
    • risk of malformations
      • are limited data on the use of buprenorphine in human pregnancies, which do not indicate associations with congenital malformations. However, data are too limited to fully exclude increased risks
      • UKTIS buprenorphine monograph has further information and guidance
    • neonatal respiratory depression
      • use of buprenorphine (as with all opioid analgesics) near the end of the third trimester may cause neonatal respiratory depression and long-term use may cause neonatal withdrawal symptoms
      • due to the long half-life of buprenorphine, neonatal monitoring for several days after birth should be considered
    • other complications
      • available data on buprenorphine exposure in human pregnancy do not indicate associations with stillbirth, preterm delivery or low infant birth weight. However, data are too limited to fully exclude increased risks
        
        
  • methadone or buprenorphine in pregnancy
    • study evidence showed (5)
      • preterm birth occurred in 14.4% of infants exposed to buprenorphine in early pregnancy and in 24.9% of those exposed to methadone and low birth weight in 8.3% and 14.9%
      • delivery by caesarean section occurred in 33.6% of pregnant persons exposed to buprenorphine in early pregnancy and 33.1% of those exposed to methadone and severe maternal complications developed in 3.3% and 3.5%, respectively
      • risk of adverse maternal outcomes was similar
      • results in late pregnancy were consistent with results of exposure in early pregnancy
        

The respective summary of product characteristics (SPCs) must be consulted before prescribing one of the drugs listed above.

Reference:

• (1) RCGP (2007). Drug misuse and dependence: UK guidelines on clinical management
• (2) NHS Specialist Pharmacy Service (April 2020).Can opioids be used for pain relief during pregnancy?
• (3) Bisson DL, Newell SD, Laxton C et al. Antenatal and postnatal analgesia. BJOG 2018; 1(26):e115-e124.
• (4) NHS Specialist Pharmacy Service (August 2022). Using opioids for pain relief during pregnancy
• (5) Suarez EA et al. Buprenorphine versus Methadone for Opioid Use Disorder in Pregnancy N Engl J Med 2022; 387:2033-2044.