Extremely preterm birth outcome: a review of four decades of cognitive research.

Premature birth incidence and survival rates are increasing steadily due to advances in obstetric and neonatal intensive care. Those born at the limits of viability are highly at-risk of adverse neurocognitive function over their lifespan, leading to current controversy regarding aggressive resuscitation efforts for these extremely preterm children. However, data from earlier generation cohorts who were born in substantially different eras of neonatal intensive care cannot be relied on to predict outcome of today's newborn. Our review by the crucial variable of birth cohort year shows a changing developmental trajectory in which today's extremely preterm survivor is likely to have fewer severe medical complications, better neurological outcomes, and fewer adverse cognitive late effects. Such data further underscore the importance of concurrently considering medical, familial, socioenvironmental, and neurobiological factors in combination with individual neonatal intensive care center protocols when studying outcomes of the preterm child. This complex, interrelated range of factors directly affects the immature, rapidly developing premature brain. However, ongoing surveillance to detect subsequent delay or impairment and to apply interventional strategies early in the developmental course holds promise for further enhancement of functional outcome.