Improving outcomes for very preterm babies in England: does place of birth matter? Findings from OPTI-PREM, a national cohort study

Objective Babies born between 27+0 and 31+6 weeks of gestation contribute substantially towards infant mortality and morbidity. In England, their care is delivered in maternity services colocated with highly specialised neonatal intensive care units (NICU) or less specialised local neonatal units (LNU). We investigated whether birth setting offered survival and/or morbidity advantages to inform National Health Service delivery.

Design Retrospective national cohort study.

Setting LNU, NICU, England.

Patients UK National Neonatal Research Database whole population data for births between 27+0 and 31+6 weeks of gestation, discharged from/died within neonatal units between 1 January 2014 and 31 December 2018. We linked baby-level data to mortality information from the Office for National Statistics.

Outcome measures Death during neonatal care, up to 1 year (infant mortality), surgically treated necrotising enterocolitis, retinopathy of prematurity, severe brain injury (SBI), bronchopulmonary dysplasia.

Intervention Birth in NICU versus LNU setting. We used an instrumental variable (maternal excess travel time between the nearest NICU and LNU) estimation approach to determine treatment effect.

Results Of 18 847 babies (NICU: 10 379; LNU: 8468), 574 died in NICU/LNU care, and 121 postdischarge (infant mortality 3.7%). We found no effect of birth setting on neonatal or infant mortality. Significantly more babies born into LNU settings experienced SBI (mean difference −1.1% (99% CI −2.2% to −0.1%)). This was attenuated after excluding births at 27 weeks, and early postnatal transfers.

Conclusions In England, LNU teams should use clinical judgement, risk assessing benefits of transfer versus risk of SBI for preterm births at 27 weeks of gestation. 28 weeks of gestation is a safe threshold for preterm birth in either NICU/LNU settings.