Managing substance use disorders during pregnancy remains a vital priority for maternal and fetal health. Neonatal opioid withdrawal syndrome represents a complex clinical challenge following intrauterine opioid exposure. Clinicians frequently wonder whether biological factors, such as infant sex, influence the severity of newborn withdrawal. Therefore, researchers conducted a secondary analysis of the Maternal Opioid Medical Supports clinical trial to evaluate this question in buprenorphine-exposed infants. Understanding these dynamics helps neonatologists and pediatricians optimize supportive care protocols.

Evaluating Infant Sex and Neonatal Opioid Withdrawal Syndrome

Perinatal clinicians frequently observe sexual dimorphism across diverse neonatal morbidities. Male infants historically face higher risks for respiratory distress, preterm complications, and sepsis. Similarly, some prior observational studies suggested that male neonates might develop more severe opioid withdrawal. Researchers hypothesized that placental steroid clearance and hormonal differences might alter fetal opioid metabolism. In addition, sex-specific differences in neurobehavioral development could theoretically increase autonomic nervous system sensitivity. However, past clinical reports often yielded conflicting conclusions due to heterogeneous cohorts and confounding substance exposures. To eliminate these confounding factors, investigators turned to the prospective Maternal Opioid Medical Supports trial. This multi-center trial enrolled pregnant individuals receiving supervised buprenorphine therapy for opioid use disorder. By evaluating a well-defined cohort, researchers sought to determine whether biological sex genuinely alters withdrawal trajectories. Clear empirical data prevent unnecessary diagnostic assumptions and help clinical teams maintain standardized monitoring pathways. Consequently, establishing whether infant sex affects clinical endpoints informs evidence-based protocols across neonatal units. Standardizing assessments ensures that clinicians evaluate all neonates purely on clinical signs rather than demographic assumptions.

Findings from the MOMS Trial on Infant Sex Differences

The investigators analyzed data from 135 infants with confirmed intrauterine buprenorphine exposure. This cohort included 67 male and 68 female newborns. Baseline maternal demographics, socioeconomic conditions, and obstetric comorbidities showed no significant differences between the two groups. The researchers utilized multivariable regression models to evaluate five primary clinical measures of withdrawal severity. Specifically, they examined receipt of any pharmacologic treatment, total days of opioid therapy, and adjunctive medication requirements. Furthermore, they measured overall hospital length of stay and withdrawal-specific hospital duration. The final regression models showed that withdrawal severity did not differ significantly by infant sex. Male and female neonates exhibited comparable odds of receiving pharmacotherapy and required similar durations of inpatient hospitalization. Consequently, these findings challenge earlier hypotheses suggesting male vulnerability in buprenorphine-exposed neonates. Rather than relying on infant sex to predict clinical outcomes, practitioners must track individual neurobehavioral symptoms. Objective clinical scoring systems remain the most reliable method for guiding therapeutic decisions. Thus, healthcare providers can confidently apply identical clinical thresholds regardless of neonatal sex.

The Clinical Impact of Polysubstance Exposure and Comorbidities

While biological sex did not correlate with withdrawal severity, maternal co-exposures produced substantial clinical effects. In this cohort, intrauterine exposure to methamphetamine and phencyclidine significantly increased the likelihood of requiring pharmacologic therapy. Additionally, phencyclidine exposure was positively associated with longer hospital stays. Polysubstance exposure complicates neonatal withdrawal because stimulant and dissociative agents disrupt multiple neurotransmitter pathways. For example, methamphetamine intensifies central nervous system irritability, hypertonia, and feeding difficulties. Unfortunately, standard opioid agonist therapies do not address these non-opioid withdrawal mechanisms. Aside from chemical exposures, delivery characteristics also strongly influenced neonatal outcomes. Both preterm delivery and neonatal intensive care unit admission significantly prolonged total hospital length of stay. Preterm neonates possess immature drug clearance mechanisms and fragile physiologic reserves, compounding withdrawal symptoms. Therefore, comprehensive antenatal substance screening remains essential. Obstetricians and addiction specialists must identify polysubstance use early to optimize maternal stabilization and prepare pediatric teams for complex postpartum care. Proactive maternal screening enables multidisciplinary teams to design targeted withdrawal monitoring protocols well before labor begins.

Protective Non-Pharmacological Interventions and Breastfeeding

In contrast to illicit co-exposures, supportive non-pharmacological care significantly mitigated withdrawal severity. The study demonstrated that maternal breastfeeding was associated with decreased receipt of pharmacologic treatment and shorter hospital stays. Breast milk transfers minimal concentrations of buprenorphine, which may provide a gentle, natural taper for the newborn. Moreover, breastfeeding promotes direct skin-to-skin contact, soothing the neonatal nervous system and stabilizing physiologic parameters. Modern clinical guidelines emphasize non-pharmacologic interventions as the primary foundation of withdrawal management. Frameworks such as the Eat, Sleep, Console model encourage continuous parental presence in quiet, low-stimulus environments. When caregivers room-in with their infants, newborns sleep longer, feed more effectively, and experience fewer severe withdrawal episodes. Clinicians should enthusiastically support breastfeeding for mothers adhering to buprenorphine maintenance therapy who have no contraindications. However, healthcare teams must assess each case individually, especially when active polysubstance use persists. Structured lactation support and compassionate counseling empower mothers to play a central role in their infant's recovery. Prioritizing non-pharmacological comfort measures noticeably reduces medication requirements and fosters maternal-infant attachment.

Implications for Perinatal Care and Future Clinical Practice

The insights from this MOMS trial secondary analysis offer practical guidance for perinatal care teams. Primarily, clinicians should not modify withdrawal monitoring intensity based on infant sex. Because male and female infants experience similar withdrawal courses, treatment decisions must depend strictly on objective bedside evaluations. Furthermore, healthcare providers should reassure pregnant patients that buprenorphine maintenance therapy remains the gold standard for opioid use disorder. Arbitrarily reducing buprenorphine dosages during pregnancy increases relapse risks and fetal instability without decreasing neonatal withdrawal severity. Instead, medical teams should focus on managing psychiatric comorbidities, preventing preterm birth, and treating polysubstance dependencies. Expanding access to integrated addiction medicine and non-stigmatizing obstetric care significantly improves dual maternal-neonatal outcomes. Although this study provides robust reassurance, larger prospective meta-analyses will further refine our understanding of neonatal pharmacokinetics. Collaborative care between obstetricians, pediatricians, and nurses remains crucial for optimizing clinical trajectories. By delivering compassionate, evidence-based care, multidisciplinary teams can support families through both delivery and recovery. Ultimately, standardized care pathways ensure every newborn receives timely intervention tailored to their specific clinical symptoms.

Frequently Asked Questions

Does infant sex influence the need for pharmacologic treatment in neonatal opioid withdrawal syndrome?

Current clinical trial evidence demonstrates that infant sex does not significantly influence the requirement for pharmacotherapy in neonatal opioid withdrawal syndrome. In the MOMS trial analysis of buprenorphine-exposed newborns, male and female infants showed equivalent rates of medication treatment, similar lengths of hospital stay, and comparable durations of opioid therapy. Therefore, pediatricians should base pharmacological decisions entirely on objective symptom scores rather than infant sex.

Why is buprenorphine preferred over unregulated opioids during pregnancy?

Buprenorphine provides stable receptor occupancy without the dangerous peaks and troughs associated with illicit opioids. Prescribed opioid agonist therapy prevents acute maternal withdrawal, prevents fetal hypoxia, and significantly reduces the risks of fatal maternal overdose. Furthermore, maintenance therapy facilitates consistent prenatal care engagement and improves neonatal growth parameters. While exposed infants may still experience withdrawal, the clinical course is generally more predictable and manageable than untreated addiction.

How does breastfeeding improve outcomes in infants with neonatal opioid withdrawal syndrome?

Breastfeeding significantly reduces withdrawal severity, decreases the need for pharmacological therapy, and shortens total hospital length of stay. Maternal milk delivers minimal, therapeutic trace amounts of buprenorphine that assist gradual weaning. Additionally, frequent skin-to-skin contact during nursing promotes autonomic regulation, lowers infant stress hormone levels, and improves maternal-infant bonding. Clinicians strongly encourage breastfeeding when mothers are stable on prescribed buprenorphine maintenance without illicit substance co-use.

Disclaimer: This content is for informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment. Healthcare professionals should exercise their independent clinical judgment. Refer to the latest local and national guidelines for clinical practice.

References

1. Wachman EM et al. Examination of Infant Sex Differences in Neonatal Opioid Withdrawal Syndrome Severity After In-Utero Buprenorphine Exposure in the MOMS Clinical Trial. J Addict Med. 2026 Nov 02. doi: 10.1097/ADM.0000000000001781. PMID: 42970777.
2. Patrick SW, Schumacher RE, Horbar JD, et al. Male Sex Associated With Increased Risk of Neonatal Abstinence Syndrome. Pediatrics. 2017;140(2):e20170552.
3. Grossman MR, Lipshaw MJ, Osborn RR, Berkwitt AK. A novel approach to assessing infants with neonatal abstinence syndrome. Hosp Pediatr. 2018;8(1):1-6.