Background and aims In Switzerland, survival of extremely preterm infants (gestational age (GA) <26 weeks) improved following the publication of the 2002 Swiss Guidelines for the care of infants born at the limit of viability, and remained stable thereafter. We compared the 2-year-outcome of survivors of cohorts born before and after the publication of the Guidelines.

Methods 2-year-outcome of surviving preterm infants (GA 22–25 weeks) born in 2000–2001 (pre-Guideline), 2003–2004 (post-Guideline), and 2005–2009 (long-term) were compared. Neurodevelopment was assessed using the BSID-II or the Griffiths Mental Development Scales. Moderate neurodevelopmental impairment (NDI) was defined as development index of -3/-2SD from the norm, or mild cerebral palsy (GMFCS level 2); severe NDI as developmental index of <-3SD from the norm, cerebral palsy (GMFCS level ≥3), deafness or blindness.

Results Of 342 survivors, follow-up data was available for 294 (86%), 29 (8%) infants were lost to follow-up, and 19 (6%) datasets were not comparable. Normal development was observed in 48%, 47% and 54%, moderate NDI in 25, 30 and 26%, and severe NDI in 19%, 10% and 15% of the cases in the pre-Guideline cohort, the post-Guideline cohort and the long-term cohort, respectively. None of these differences over time were significant (χ², p > 0.1).

Conclusion 2-year-outcome in survivors after extremely preterm birth remained stable despite improved survival rates following the publication of the Guidelines for the care of infants born at the limit of viability.