Naltrexone (Vivitrol, ReVia, Depade) is a medication approved to treat both Opioid Use Disorder (OUD) and Alcohol Use Disorder (AUD). As an opioid antagonist, it blocks the effects of opioid drugs and reduces alcohol craving. Using any medication during pregnancy requires a careful assessment to balance the risks of exposure against the harms of the untreated condition. This decision must be made collaboratively between the pregnant individual and their healthcare provider, considering the limited safety data available for many drugs in this population.
The Current Medical Consensus on Use During Pregnancy
The standard of care for Opioid Use Disorder (OUD) in pregnancy is generally opioid agonist medications like Methadone or Buprenorphine, not Naltrexone. This preference is due to the extensive, long-term data supporting the safety and efficacy of agonist therapies. Starting Naltrexone in an opioid-dependent person would immediately cause severe and potentially dangerous acute withdrawal, concerning both the mother and the fetus.
Naltrexone is an option for pregnant individuals with OUD who have successfully completed detoxification and are completely abstinent. Retrospective studies in this context show favorable outcomes, including a significantly lower rate of Neonatal Opioid Withdrawal Syndrome (NOWS) compared to infants exposed to agonist therapies. For Alcohol Use Disorder (AUD), Naltrexone may be considered case-by-case, though counseling and behavioral therapies are often the first steps.
The safety data for Naltrexone use during human pregnancy remains limited, primarily coming from small case series and retrospective studies. Animal studies conducted at high doses suggested potential adverse effects, such as increased early fetal loss in some species. In 2015, the U.S. Food and Drug Administration (FDA) replaced the former letter-based pregnancy categories with the Pregnancy and Lactation Labeling Rule (PLLR). This new system requires drug labels to provide a narrative summary of risks and clinical considerations, emphasizing that treatment benefits must outweigh potential risks.
Clinical guidelines suggest that if a patient is stable on Naltrexone when they become pregnant, the decision to continue involves weighing limited safety data against the significant risk of relapse if stopped. The drug crosses the placenta, and maternal and fetal levels are concordant, meaning the fetus is exposed. For patients initiating Naltrexone, some protocols recommend careful fetal monitoring during the first dose, especially if initiated after 24 weeks gestation, to monitor for fetal distress.
Balancing Risks: Untreated Substance Use vs. Medication Exposure
The decision to continue or initiate Naltrexone involves a complex risk-benefit calculation, as the dangers of untreated substance use disorder often outweigh medication risks. Untreated Opioid Use Disorder (OUD) carries severe risks for the mother, including malnutrition, infectious disease exposure, poor prenatal care, and a high likelihood of overdose and death.
For the fetus, untreated OUD is associated with a greater risk of:
- Preterm birth.
- Stillbirth.
- Fetal growth restriction.
- Fetal distress.
Untreated Alcohol Use Disorder (AUD) can lead to Fetal Alcohol Spectrum Disorders (FASDs), causing permanent physical and neurodevelopmental disabilities.
A provider may maintain Naltrexone in a stable patient because discontinuing the medication can destabilize recovery and increase the risk of illicit substance use and overdose. The clinical rationale emphasizes that maintaining maternal stability and sustained abstinence is the primary goal for improving pregnancy outcomes. The known, significant harms of untreated OUD and AUD provide a strong argument for continuing effective treatment despite limited human data.
The decision-making process must account for the individual’s history, motivation, support system, and the Naltrexone formulation (oral or extended-release injection). The goal is to minimize overall risk; maintaining a stable recovery with medication is often considered the safer path than risking a return to active substance use.
Alternative Treatment Pathways for Substance Use During Pregnancy
When Naltrexone is not optimal for Opioid Use Disorder (OUD), the preferred treatments are Medication-Assisted Treatments (MAT) using opioid agonists, specifically Methadone and Buprenorphine. These medications are the standard of care because they effectively reduce cravings and withdrawal symptoms, stabilizing the patient and allowing for better engagement in prenatal care. Methadone has been successfully used to treat pregnant individuals with OUD since the 1970s, and Buprenorphine has also demonstrated positive outcomes.
Agonist therapies occupy opioid receptors without causing a euphoric high, preventing withdrawal and blocking the effects of other opioids. While effective, Methadone and Buprenorphine exposure can lead to Neonatal Opioid Withdrawal Syndrome (NOWS) in the newborn. NOWS is an expected and treatable condition, characterized by symptoms such as irritability, tremors, and poor feeding, often requiring a longer hospital stay for monitoring and treatment.
Naltrexone is an opioid antagonist and does not carry the risk of causing NOWS because it blocks the opioid receptors rather than activating them. Avoiding NOWS is a major advantage of Naltrexone when used in pregnant individuals who are fully abstinent from opioids. For Alcohol Use Disorder (AUD), first-line treatment involves psychosocial support, counseling, and behavioral therapies. If pharmacological intervention is needed, Naltrexone is one of the few options, but limited safety data means it is reserved for cases where relapse risk is high and non-medication approaches have failed.
Monitoring and Post-Natal Considerations
If Naltrexone was used throughout pregnancy, the focus shifts to intensive maternal monitoring and specific observation protocols for the newborn. Maternal monitoring is essential to ensure continued abstinence and prevent relapse, which can be devastating postpartum. Because Naltrexone clears quickly, especially the oral formulation, a missed dose could leave the mother vulnerable to relapse.
Newborns exposed to Naltrexone in utero are monitored for signs of distress but do not experience NOWS. Studies show that Naltrexone-exposed infants have significantly shorter hospital stays compared to those exposed to opioid agonist medications. All exposed infants are closely observed for subtle signs of issues, such as feeding difficulties or irritability.
Regarding lactation, Naltrexone is generally considered compatible with breastfeeding, though caution is advised due to limited research. Studies show that the amount of Naltrexone transferred to the infant through breast milk is low. Clinicians weigh the known benefits of breastfeeding against the minimal drug exposure.