Outcome of Extreme Prematurity: A Prospective Comparison of 2 Regional Cohorts Born 20 Years Apart

Abstract

OBJECTIVE: To determine changes that have occurred over the past 20 years in perinatal characteristics, neonatal treatments, morbidities, and early neurodevelopmental outcomes of infants born at ≤30 weeks' gestation. METHODS: This was a prospective regional study including all live-born infants ≤30 weeks' gestation born between July 1985 and June 1986 (cohort 1) and July 2005 and June 2006 (cohort 2). Sociodemographically matched term controls were recruited for each cohort. Perinatal characteristics, mortality rates, and survival with and without impairments at 24 months' corrected age were compared. RESULTS: There was a 35% increase in the number of live-born preterm births (138 in cohort 1 and 187 in cohort 2) despite a >10% decline in total births in the region (P < .001). Assisted fertility (rarely available for mothers in cohort 1) was responsible for 20% of pregnancies in cohort 2. Survival to hospital discharge increased over 20 years from 82% to 93% (P = .002), primarily because of higher survival for infants born at <27 weeks' gestation (63% vs 88%; P = .004). Changes in management in cohort 2 included the use of surfactant (62% of infants) and increased use of postnatal steroids (39% vs 9%; P < .001), that were associated with a shorter median duration of mechanical ventilation (13 vs 21 days; P < .001); however, the incidence of bronchopulmonary dysplasia was higher in cohort 2 (56% vs 35%; P < .001). There was a significant decrease in incidence of severe ultrasound abnormalities from 17% in cohort 1 to 7% in cohort 2 (P = .008). At 24 months of age, 7% of cohort 1 and 5% of cohort 2 had an abnormal neurologic exam. Bayley cognitive scores were improved in cohort 2 (significantly closer to the mean of their controls). As a result, survival without severe neurodevelopmental impairment increased from 62% in cohort 1 to 81% in cohort 2 (P < .001). CONCLUSION: Over 20 years, there has been a significant increase in live births at ≤30 weeks' gestational age, with a greater percentage of these neonates surviving without severe neurodevelopmental impairment at 24 months.