Infant autonomic functioning and neonatal abstinence syndrome.

Area of Science:

• Neonatology
• Autonomic Nervous System Regulation
• Pharmacology

Background:

• Neonatal Abstinence Syndrome (NAS) severity varies widely, with underlying mechanisms poorly understood.
• Prenatal drug exposure may lead to autonomic dysregulation, specifically affecting vagal tone.
• Cardiac vagal tone is an indicator of parasympathetic neuroregulation and may serve as a marker for autonomic dysregulation in NAS.

Purpose of the Study:

• To investigate if cardiac vagal tone serves as a marker for autonomic dysregulation in prenatally opioid-exposed newborns.
• To examine the relationship between cardiac vagal tone and the expression of NAS symptoms.
• To identify predictors of NAS severity and duration of hospitalization.

Main Methods:

• Electrocardiogram data were used to derive heart period (HP) and cardiac vagal tone (V) in 64 methadone-exposed infants.
• Measurements were taken on postnatal days 1 and 3, with serial assessment of the postpartum NAS course.
• Toxicology screening throughout pregnancy assessed poly-drug exposure.

Main Results:

• Lower cardiac vagal tone on day 1 was significantly associated with higher NAS symptomatology on day 3.
• Male infants exhibited more severe NAS symptoms and required longer treatment and hospitalization.
• Greater poly-drug exposure, particularly cocaine use, was linked to lower V and shorter HP.
• Infant sex, SSRI/SNRI use, and smoking predicted NAS symptoms and hospitalization duration.

Conclusions:

• Findings support a biologic vulnerability in autonomic regulation for infants exposed to methadone.
• Male infants demonstrate a greater vulnerability to maternal methadone use and subsequent NAS expression.
• Cardiac vagal tone is a potential biomarker for autonomic dysregulation in NAS.