Changes in neurodevelopmental outcome at age eight in geographic cohorts of children born at 22-27 weeks' gestational age during the 1990s

Background: The survival rate for children born with gestational ages 22-27 weeks is increasing, and this may be associated with higher rates of disability. The aims of this study were to determine the outcomes at age eight for a regional cohort of children born at 22-27 weeks during 1997, and to compare their rates of disability with a cohort of the same gestational age born in 1991-1992. Methods: Consecutive children with gestational ages in the range 22-27 weeks born in the state of Victoria, Australia, in 1997 and matched term controls were assessed at 8 years. Outcomes included blindness, deafness, cerebral palsy (CP) and intellectual impairment and disabilities caused by these impairments. These outcomes were compared with a cohort of 22-27-week and term children born in 1991-1992 in the same region. Results: Follow-up rates for the 1997 cohort at 8 years of age were 95% (144/151) for 22-27 weeks survivors and 89% (173/195) for controls. Rates of disability were substantially higher in the preterm cohort than the controls. The 1997 and 1991-1992 preterm cohorts had similar rates of moderate or severe disability (19%), however the rate of mild impairment was greater in 1997 (40% vs 24%). Rates of disability were almost identical in control groups. Intellectual impairment and CP were the major reasons for the higher rates of disability. Conclusions: The high prevalence of adverse neurodevelopmental outcome in children born at 22-27 weeks compared with term controls at school age persists, and may even be increasing over time.