Transferring extremely premature babies from a lower ("non-tertiary") level neonatal care unit to a higher ("tertiary") level unit in the first 48 hours after birth is associated with an increased risk of severe brain injury, finds a study published by The BMJ today.
Keeping these infants at lower level units after birth is also associated with a higher risk of death, compared with birth in a tertiary facility.
The findings are based on more than 17,000 births in England between 2008 and 2015, and suggest that neonatal services should be designed to ensure, whenever possible, that extremely preterm infants are born in a tertiary care setting.
About one in 20 premature infants in high income countries are born extremely prematurely (at less than 28 weeks of pregnancy) and are at high risk of death, severe illness, and long term disability.
Studies from the 1980s found that transporting preterm infants from non-tertiary to tertiary care shortly after birth (known as "early postnatal transfer") was linked to worse outcomes than preterm infants born in a tertiary setting.
But results from recent studies have been inconclusive, and care for the most premature babies before and after birth has changed considerably since many of these studies were done.
In England, early postnatal transfer continues to increase since neonatal care was reorganised in 2007, so it's important to understand any effects associated with this.
To explore this further, researchers based in Finland and the UK analysed data for 17,577 extremely premature infants (born at less than 28 gestational weeks) in NHS hospitals in England between 2008 and 2015.
Infants were grouped based on birth hospital and transfer within 48 hours. Factors that could have influenced the results, like gestational age and whether antenatal steroids were given, were also taken into account by forming matched groups of babies.
Compared with controls (tertiary birth; not transferred), infants born in a non-tertiary hospital and transferred to a tertiary hospital had no significant difference in risk of death before discharge but higher risk of severe brain injury and lower chance of survival without severe brain injury.
Infants born in a non-tertiary hospital and not transferred had higher risk of death but no difference in risk of severe brain injury or survival without severe brain injury, compared with controls.
No differences in outcomes were found for infants transferred between tertiary hospitals (for non-medical reasons, such as insufficient capacity) and controls.
All these results were largely unchanged after further sensitivity analyses, suggesting that the findings withstand scrutiny.
This is an observational study, and as such, can't establish cause, and the authors cannot rule out the possibility that some of the outcomes may have been due to other unmeasured (confounding) factors.
Nevertheless, they say this is one of the largest and most robust studies to focus on major outcomes among the highest risk infants in the context of modern neonatal care, and the results are in line with previous work in this field.
As such, they conclude: "Extremely preterm birth in a non-tertiary setting is associated with a higher risk of death and lower survival without severe brain injury compared with infants born in a tertiary neonatal setting." They also recommend perinatal health services "promote pathways that facilitate delivery of extremely preterm infants in tertiary hospitals in preference to postnatal transfer."
This view is supported by US researchers in a linked editorial, who say transfer before not after birth is the best approach for women at risk of preterm labour.
Professor Colm Travers from the University of Alabama at Birmingham and colleagues point out that antenatal transfer is well established in some US states, Australia and Scandinavia, where up to 95% of at risk infants are transferred before birth.
"Improved regionalization of perinatal care, prioritizing early and clear transfer pathways for women with threatened preterm labor should increase survival and reduce major lifelong morbidities among extremely preterm infants," they conclude.
Peer-reviewed? Yes (research); No (linked editorial)
Evidence type: Observational; Opinion
Subjects: Extremely preterm infants