Changing Dutch approach and trends in short-term outcome of periviable preterms.

Background: In 2006, the Dutch guideline for active treatment of extremely preterm neonates advised to lower the gestational age threshold for active intervention from 26 0/7 to 25 0/7 weeks gestation.

Objective: To evaluate the association between the guideline modification and early neonatal outcome.

Design: National cohort study, using prospectively collected data from The Netherlands Perinatal Registry.

Patients: The study population consisted of 9713 infants with a gestational age between 24 0/7 and 29 6/7 weeks, born between 2000 and 2011. Three gestational age subgroups were analysed: 24 0/7 to 24 6/7 weeks (n=269), 25 0/7 to 25 6/7 weeks (n=852) and 26 0/7 to 29 6/7 weeks (n=8592).

Main Outcome Measures: Neonatal intensive care unit (NICU) admission, live births, neonatal in-hospital mortality, morbidity and favourable outcome (no mortality or morbidity) before (2000-2005; period 1) and after (2007-2011; period 2) introduction of the modified guideline, using χ(2) tests and univariable and multivariable logistic regression analyses.

Results: In the second period, the proportion of live births and NICU admissions increased and the proportion of neonatal and in-hospital mortality decreased significantly in all subgroups. Morbidity in surviving infants of 25 weeks increased significantly, although the association between guideline modification and morbidity became non-significant after case-mix adjustment. Overall, favourable outcome did not change significantly after guideline modification in all subgroups when adjusted for variation in case-mix.

Conclusions: Overall, the trend in mortality gradually declined at all gestational ages, starting before 2006. This suggests that the guideline modification was a formalisation of already existing daily practice.