Temporal Trends in Neurodevelopmental Outcomes to 2 Years After Extremely Preterm Birth

IMPORTANCE Survival of infants born extremely preterm (EP) (<28 weeks' gestation) has increased since the early 1990s. It is necessary to know whether increased survival is accompanied by increased neurodevelopmental disability. OBJECTIVE To examine changes in major (ie, moderate or severe) neurodevelopmental disability and survival free of major neurodevelopmental disability at 2 years in infants born EP. DESIGN, SETTING, AND PARTICIPANTS Four prospective longitudinal cohort studies comprising all EP live births at 22 to 27 weeks' gestation from April 1, 2016, to March 31, 2017, and earlier eras (1991-1992, 1997, and 2005), and contemporaneous term-born controls in the state of Victoria, Australia. Among 1208 live births during the periods studied, data were available for analysis of 2-year outcomes in 1152 children: 422 (1991-1992), 215 (1997), 263 (2005), and 252 (2016-2017). Data analysis was performed from September 17, 2020, to April 15, 2021. EXPOSURES Extreme preterm live birth. MAIN OUTCOMES AND MEASURES Survival, blindness, deafness, cerebral palsy, developmental delay, and neurodevelopmental disability at 2 years' corrected age. Developmental delay comprised a developmental quotient less than -1 SD relative to the control group means on the Bayley Scales for each era. Major neurodevelopmental disability comprised blindness, deafness, moderate to severe cerebral palsy, or a developmental quotient less than -2 SDs. Individual neurodevelopmental outcomes in each era were contrasted relative to the 2016-2017 cohort using logistic regression adjusted for gestational age, sex, birth weight z score, and sociodemographic variables. Changes in survival free of major neurodevelopmental disability over time were also assessed using logistic regression. RESULTS Survival to 2 years was highest in 2016-2017 (73%[215 of 293]) compared with earlier eras (1991-1992: 53%[225 of 428]; 1997: 70% [151 of 217]; 2005: 63%[170 of 270]). Blindness and deafness were uncommon (<3%). Cerebral palsy was less common in 2016-2017 (6%) than in earlier eras (1991-1992: 11%; 1997: 12%; 2005: 10%). There were no obvious changes in the rates of developmental quotient less than -2 SDs across eras (1991-1992: 18%; 1997: 22%; 2005: 7%; 2016-2017: 15%) or in rates of major neurodevelopmental disability (1991-1992: 20%; 1997: 26%; 2005: 15%; 2016-2017: 15%). Rates of survival free of major neurodevelopmental disability increased steadily over time: 42%(1991-1992), 51%(1997), 53%(2005), and 62%(2016-2017) (odds ratio, 1.30; 95% CI, 1.15-1.48 per decade; P<.001). CONCLUSIONS AND RELEVANCE These findings suggest that survival free of major disability at age 2 years in children born EP has increased by an absolute 20% since the early 1990s. Increased survival has not been associated with increased neurodevelopmental disability.