Transfer Patterns Among Infants Born at 28 to 34 Weeks' Gestation.

Background: Although postnatal transfer patterns among high-risk (eg, extremely preterm or surgical) infants have been described, transfer patterns among lower-risk populations are unknown. The objective was to examine transfer frequency, indication, timing, and trajectory among very and moderate preterm infants.

Methods: Observational study of the US Vermont Oxford Network all NICU admissions database from 2016 to 2021 of inborn infants 280/7 to 346/7 weeks. Infants' first transfer was assessed by gestational age, age at transfer, reason for transfer, and transfer trajectory.

Results: Across 467 hospitals, 294 229 infants were eligible, of whom 12 552 (4.3%) had an initial disposition of transfer. The proportion of infants transferred decreased with increasing gestational age (9.6% [n = 1415] at 28 weeks vs 2.4% [n = 2646] at 34 weeks) as did the median age at time of transfer (47 days [interquartile range 30-73] at 28 weeks vs 8 days [interquartile range 3-16] at 34 weeks). The median post menstrual age at transfer was 34 or 35 weeks across all gestational ages. The most common reason for transfer was growth or discharge planning (45.0%) followed by medical and diagnostic services (30.2%), though this varied by gestation. In this cohort, 42.7% of transfers were to a higher-level unit, 10.2% to a same-level unit, and 46.7% to a lower-level unit, with indication reflecting access to specific services.

Conclusions: Over 4% of very and moderate preterm infants are transferred. In this population, the median age of transfer is later and does not reflect immediate care needs after birth, but rather the provision of risk-appropriate care.