Neonatal abstinence syndrome in Norway - a registry study

Medications and illicit substances taken during pregnancy are transferred to the foetus via the placenta. When the supply ceases after birth, the infant can develop withdrawal symptoms. The aim of the study was to investigate the incidence, neonatal morbidity and regional differences in hospital admissions of infants with neonatal abstinence syndrome (NAS) in Norway.

Using the Norwegian Neonatal Network quality registry, we identified all neonates in Norway with a gestational age of ≥ 36 weeks who were discharged from a neonatal unit and diagnosed with NAS during the study period from 1 January 2012 to 31 December 2023. We extracted key register data, including additional diagnoses and length of stay in the neonatal unit.

We identified 621 neonates with NAS over the 12-year period, corresponding to a national incidence of 0.95 per 1,000 liveborn infants with a gestational age of ≥ 36 weeks. The median length of stay in a neonatal unit for all infants included in the study was 6-8 days throughout the study period. However, the hospital stay was ≥ 14 days for 134 infants (22%). A total of 119 infants (19%) had a birth weight below the 10th percentile, defined as small for gestational age. Seven infants (1%) were diagnosed with neonatal seizures. Congenital heart defects were identified in 14 infants (2%).

The incidence of NAS in Norway was lower than reported figures in other Western countries. Consistent with findings in the literature, one in five infants with NAS were small for gestational age.