Maternal Opioid Dose Does Not Predict Newborn Withdrawal Severity
A new study finds that the severity of neonatal opioid withdrawal syndrome is not linked to a mother's medication dose or drug levels in the umbilical cord, challenging a common clinical assumption.
New research challenges the assumption that a mother's opioid medication dose directly determines the severity of her newborn's withdrawal. A study analyzing 92 pregnancies found no link between maternal dose or umbilical cord drug levels and the intensity of neonatal opioid withdrawal syndrome (NOWS).
The study analyzed data from 92 pregnancies that produced 94 neonates. The mothers had a median age of 31.0 years. The cohort was predominantly White, with most participants having public insurance and smoking during pregnancy being common. All participants received methadone or buprenorphine for opioid use disorder for at least 30 days before delivery. Researchers from the University of Maryland School of Medicine measured concentrations of the medications and their metabolites in umbilical cord tissue to assess fetal exposure during the final trimester.
Key findings on medication type and withdrawal severity
41 neonates, or about 44 percent, developed severe withdrawal syndrome. This severe condition may be accompanied by seizures, vomiting, fever, or hypothermia. The rate of severe NOWS was significantly higher among newborns exposed to methadone compared to those exposed to buprenorphine.
| Medication | Rate of Severe NOWS | Adjusted Odds Ratio for Severe NOWS |
|---|---|---|
| Methadone | 55.6% | 3.42 (95% CI: 1.17-9.96) |
| Buprenorphine | 27.5% | Reference |
Despite this difference in outcomes based on medication type, no significant association was found between the mother's medication dose and withdrawal severity. Also, no significant differences in umbilical cord medication concentrations were found between newborns with severe withdrawal and those with less severe symptoms.
Dose levels and cord concentrations analyzed
The analysis delved deeper into the relationship between dosing, fetal exposure, and outcomes. Higher maternal methadone doses did correspond with higher cord concentrations of methadone and its metabolite EDDP. For buprenorphine, no significant relationship emerged between the maternal dose and cord levels of the drug or its metabolite.
Crucially, cord concentrations of the medications were similar in neonates with and without severe NOWS. Maternal dosing patterns were also similar for both groups. The peak Finnegan scores used to assess withdrawal showed no correlation with maternal dose or cord drug levels for either medication. The amount of medication reaching the fetus, as measured in cord tissue, does not explain which newborns will experience more severe withdrawal.
Study limitations and author recommendations
The authors noted the study's limitations, including its small sample size and limited racial and ethnic diversity of participants. They cautioned against lowering medication for opioid use disorder (MOUD) doses during pregnancy to protect newborns from severe withdrawal. The results do not support reducing maternal medication doses as a strategy to prevent severe NOWS.
Instead, the authors recommended continuing to tailor MOUD dosing to each patient's clinical stability to reduce relapse and overdose risk. Medication doses should be selected for effective treatment of the mother rather than reduced to prevent withdrawal syndrome in the child. Pregnant patients receiving medication for opioid use disorder should not reduce their medication dose out of fear it will worsen newborn withdrawal symptoms. Appropriate monitoring and care for newborns exposed to opioids is still needed. The study shows the need to balance newborn care with the health and safety of pregnant patients. The article closes on the authors' recommendation that clinicians maintain effective treatment for the pregnant patient rather than lowering doses to attempt to prevent neonatal withdrawal.
