Neurodevelopmental outcomes for preterm infants show no improvement since 1990s

1. Rates of major neurosensory disability, IQ <-2 SD, cerebral palsy (CP), blindness, and deafness were similar at 8 years among premature infants born in 3 different eras since the 1990s.

2. Academic achievement scores at age 8, including word reading, spelling, and mathematics, were lower among premature infants born in 2005 compared with those in 1997.

Evidence Rating Level: 2 (Good)

Study Rundown: The use of exogenous surfactant to treat respiratory distress syndrome starting in the early 1990s has increased survival rates among extremely premature (EP; 22-27 weeks gestation) infants in Australia. Prior studies showed higher rates of adverse neurodevelopmental outcomes for EP survivors born in the 1990s compared to term infants. Subsequently, starting in the 2000s, increased use of caffeine and decreased use of postnatal corticosteroids were expected to improve long-term neurodevelopmental outcomes in EP infants; however no studies have compared outcomes among EP survivors from the different eras. This study compared neurodevelopmental outcomes at 8 years among EP infants and control term infants in Victoria, Australia born during 3 different eras: 1991-1992, 1997, and 2005. Results showed similar rates of neurosensory disability, IQ <-2SD, CP, blindness, and deafness among the 3 cohorts. The odds of EP survivors having academic problems were higher in the 2005 cohort than in the earlier 2 eras. One major limitation of this study is variation in the cognitive assessments used between each cohort. Results from this study suggest a need to identify modifiable risk factors and treatments for EP infants that will improve long-term cognitive and neurodevelopmental outcomes.

Click to read the study, published today in Pediatrics

Relevant reading: An overview of mortality and sequelae of preterm birth from infancy to adulthood

In-depth [prospective cohort]: Participants included all (N=915) EP live-born infants at birth, born during 3 distinct eras in Victoria, Australia: 1991-1992, 1997, and 2005. Control infants born during the same time periods were also recruited and matched with EP survivors based on expected date of birth, sex, and other perinatal and sociodemographic characteristics. All participants were evaluated at 8 years of age (corrected for prematurity) by pediatricians and psychologists blinded to clinical details. Children were evaluated for markers of neurodevelopment, with major neurosensory disability defined as any of moderate or severe CP, blindness, deafness or an IQ<-2 SD. Results showed rates of major neurosensory disability were similar among EP infants from all 3 eras (1991-1992, 18%; 1997, 15%; 2005, 18%). IQ and academic achievement scores were significantly? higher among all controls compared to EP children in all cohorts, but mean IQ scores did not significantly change among EP infants across the eras (1991-1992, 94.9; 1997, 93.8; 2005, 94.7), nor did percent of EP infants with IQ z score <-2 SD (1991-1992, 14%; 1997, 10%; 2005, 14%). Word reading, spelling, and mathematics scores were all lower in 2005 EP infants compared with EP infants from the 1997 group, even after adjustment for perinatal variables (age of mother, sociodemographic variables, etc.). Among EP infants from all 3 eras, factors including cystic periventricular leukomalacia, postnatal corticosteroids, lower social class and lower maternal education were related to more adverse outcomes, whereas increasing gestational age and higher birth weight were associated with better outcomes.

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