Norwegian registry study reports neonatal abstinence syndrome in 0.95 per 1,000 births

A nationwide observational study using the Norwegian Neonatal Network quality registry examined neonatal abstinence syndrome (NAS) during 2012–2023. Researchers identified 621 infants born at ≥36 weeks who were discharged from neonatal units with a NAS diagnosis. The study assessed incidence, neonatal morbidity and regional differences in hospital admission and length of stay. NAS can occur after prenatal exposure to medications or illicit substances ends at birth.

The national incidence was 0.95 per 1,000 liveborn infants at ≥36 weeks’ gestation. Median neonatal-unit length of stay was 6–8 days throughout the study period, although 134 infants (22%) stayed at least 14 days. Birth weight was below the 10th percentile in 119 infants (19%), meeting the definition of small for gestational age. Seven infants (1%) had neonatal seizures, and 14 (2%) had congenital heart defects.

The authors reported a lower incidence than figures published for other Western countries. The findings describe a substantial subgroup requiring prolonged admission and a frequent occurrence of small-for-gestational-age birth weight. However, the study population was restricted to infants born at ≥36 weeks with diagnosed NAS who received neonatal-unit care. These observational findings do not establish that NAS caused the associated neonatal conditions.