Paralleling the large recent increases in opioid use, use disorder, and overdose, the incidence of babies born dependent on opioids (neonatal abstinence syndrome, or NAS) as a result of the mother’s opioid use during pregnancy has also greatly increased.5 Incidence of NAS rose nearly fivefold between 2000 and 2012;4 this increase was associated with increases in the prescription of opioids to pregnant women for pain, which doubled between 1995 and 2009.99,100
Untreated opioid use disorder during pregnancy can have devastating effects on the fetus. The fluctuating levels of opioids in the blood of mothers misusing opioids expose the fetus to repeated periods of withdrawal,101 which can also harm the function of the placenta and increase the risk of:
- fetal growth restriction101
- placental abruption101
- preterm labor101
- fetal convulsions101
- intrauterine passage of meconium101
- fetal death102
In addition to these direct physical effects, other risks to the fetus include:
- untreated maternal infections such as HIV103
- malnutrition and poor prenatal care104
- dangers conferred by drug-seeking lifestyle, including violence and incarceration102,104
Methadone and Buprenorphine as the Standard of Care for Opioid Use Disorder in Pregnancy
To lessen the negative effects of opioid dependence on the fetus, treatment with methadone has been used for pregnant women with opioid use disorder since the 1970s and has been recognized as the standard of care since 1998.102,103 Recent evidence, however, suggests that buprenorphine may be an even better treatment option.105
Both methadone and buprenorphine treatment during pregnancy:
- stabilize fetal levels of opioids, reducing repeated prenatal withdrawal101,106
- improve neonatal outcomes104
- increase maternal HIV treatment to reduce the likelihood of transmitting the virus to the fetus102–104
- link mothers to better prenatal care102,104
A meta-analysis showed that, compared to single-dose methadone treatment, buprenorphine resulted in:
- 10 percent lower incidence of NAS
- shorter neonatal treatment time (an average of 8.4 days shorter)
- lower amount of morphine used for NAS treatment (an average of 3.6 mg lower)
- higher gestational age, weight, and head circumference at birth105
Data from the NIDA-funded Maternal Opioid Treatment: Human Experimental Research study show similar benefits of buprenorphine.107 Still, methadone is associated with higher treatment retention than buprenorphine.105 Divided dosing with methadone has been explored as a way to reduce fetal exposure to withdrawal periods, and recent data show low levels of NAS in babies born to mothers treated with divided doses of methadone.108 Larger comparison studies are needed to determine if split methadone dosing for opioid use disorders in pregnancy is associated with better outcomes.
NAS still occurs in babies whose mothers have received buprenorphine or methadone, but it is less severe than it would be in the absence of treatment.109 Research does not support reducing maternal methadone dose to avoid NAS, as this may promote increased illicit drug use, resulting in increased risk to the fetus.101
