Objectives To describe 2-year neurodevelopmental outcome (NDO) in a cohort of extremely low birthweight infants, and compare NDO between two consecutive 5-year periods and between appropriate (AGA, ≥p10) and small for gestational age (SGA, <p10) infants.

Design Retrospective cohort study.

Setting Wilhelmina Children's Hospital, Utrecht, the Netherlands.

Patients 146 children, born between 1996 and 2005, with a birth weight ≤750 g and a gestational age ≥24 weeks, admitted to the neonatal intensive care unit. 111 children (76%) survived the neonatal period.

Interventions At 2 years corrected age, 101 children (cohort I: born in 1996–2000, n=45 and cohort II: born in 2001–2005, n=56) were assessed with either the Griffiths Mental Developmental Scales or the Mental Scale of the Bayley Scales of Infant Development, second edition.

Main outcome measures NDO, classified as normal (≤−1 Z score ≥0), mildly delayed (>−1 Z score ≤−2) or severely delayed (Z score >−2).

Results 74.3% of the children had a normal NDO at 2 years corrected age, 20.8% a mildly and 5% a severely delayed outcome. Although survival significantly increased with time (65.8% to 88.1%, p=0.002), significantly fewer children in cohort II (66.1% vs 84.4% in cohort I, p=0.042) as well as fewer SGA children (64.3% vs 86.7% of AGA children, p=0.012) had a normal NDO.

Conclusions Increased survival of infants with a birth weight ≤750 g coincided with more children with an impaired NDO at 2 years corrected age. SGA infants are especially at risk of impaired NDO.