Importance: Active perinatal care increases survival of extremely preterm infants; however, improved survival might be associated with increased disability among survivors.
Objective: To determine neurodevelopmental outcome in extremely preterm children at 2.5 years (corrected age).
Design, setting, and participants: Population-based prospective cohort of consecutive extremely preterm infants born before 27 weeks of gestation in Sweden between 2004 and 2007. Of 707 live-born infants, 491 (69%) survived to 2.5 years. Survivors were assessed and compared with singleton control infants who were born at term and matched by sex, ethnicity, and municipality. Assessments ended in February 2010 and comparison estimates were adjusted for demographic differences.
Main outcomes and measures: Cognitive, language, and motor development was assessed with Bayley Scales of Infant and Toddler Development (3rd edition; Bayley-lll), which are standardized to mean (SD) scores of 100 (15). Clinical examination and parental questionnaires were used for diagnosis of cerebral palsy and visual and hearing impairments. Assessments were made by week of gestational age.
Results: At a median age of 30.5 months (corrected), 456 of 491 (94%) extremely preterm children were evaluated (41 by chart review only). For controls, 701 had information on health status and 366 had Bayley-lll assessments. Mean (SD) composite Bayley-III scores (cognition, 94 [12.3]; language, 98 [16.5]; motor, 94 [15.9]) were lower than the corresponding mean scores for controls (cognition, 104 [10.6]; P < .001; adjusted difference in mean scores, 9.2 [99% CI, 6.9-11.5]; language, 109 [12.3]; P < .001; adjusted difference in mean scores, 9.3 [99% Cl, 6.4-12.3]; and motor, 107 [13.7]; P < .001; adjusted difference in mean scores, 12.6 [99% Cl, 9.5-15.6]). Cognitive disability was moderate in 5% of the extremely preterm group vs 0.3% in controls (P < .001) and it was severe in 6.3% of the extremely preterm group vs 0.3% in controls (P < .001). Language disability was moderate in 9.4% of the extremely preterm group vs 2.5% in controls (P < .001) and severe in 6.6% of the extremely preterm group vs 0% in controls (P < .001). Other comparisons between the extremely preterm group vs controls were for cerebral palsy (7.0% vs 0.1%; P < .001), for blindness (0.9% vs 0%; P = .02), and for hearing impairment (moderate and severe, 0.9% vs 0%; P = .02, respectively). Overall, 42% (99% CI, 36%-48%) of extremely preterm children had no disability, 31% (99% CI, 25%-36%) had mild disability, 16% (99% CI, 12%-21%) had moderate disability, and 11% (99% CI, 7.2%-15%) had severe disability. Moderate or severe overall disability decreased with gestational age at birth (22 weeks, 60%; 23 weeks, 51%; 24 weeks, 34%; 25 weeks, 27%; and 26 weeks, 17%; P for trend < .001).
Conclusions and relevance: Of children born extremely preterm and receiving active perinatal care, 73% had mild or no disability and neurodevelopmental outcome improved with each week of gestational age. These results are relevant for clinicians counseling families facing extremely preterm birth.