Neurodevelopmental outcome after extreme prematurity: a review of the literature

Background: Advances in obstetric and neonatal medical care and assisted reproductive technology have increased the rates of preterm birth, decreased preterm mortality rates, and lowered the limit of viability. However, morbidity in survivors, including neurodevelopmental disabilities, has increased, especially in extremely preterm infants born at ≤25 weeks' gestation. A better understanding of the prevalence and patterns of adverse neurodevelopmental outcomes in extremely preterm infants is important for patient care, counseling of families, and research.

Methods: The PubMed and Ovid Medline databases were searched for full text articles published between 1999 and 2013 in English that reported neurodevelopmental outcomes after extreme prematurity, and a review of identified relevant cohort studies was performed.

Results: Extreme prematurity of 22 to 25 weeks' gestation is associated with an overall high mortality of ≥50%. High rates (17% to 59%) of severe neurodevelopmental disabilities occur among survivors on short-term follow-up. The rates of surviving unimpaired or minimally impaired are 6% to 20% for live-born infants at ≤25 weeks' gestation and <5% for infants born at 22 and 23 weeks' gestation. Long-term adverse outcomes after extreme prematurity include intellectual disability (5% to 36%), cerebral palsy (9% to 18%), blindness (0.7% to 9%), and deafness (2% to 4%). Milder degrees of disability involving cognition, behavior, and learning are increasingly recognized among older preterm children, teens, and young adults.

Conclusions: Infants who are born at ≤25 weeks' gestation, especially those born at 22 and 23 weeks' gestation, have a very low likelihood of surviving little or no impairment. Nearly half of surviving extremely premature infants have significant neurodevelopmental disabilities on short- and long-term follow-up. Instituting early intervention programs, providing family support, and establishing special educational school programs can pay high dividends and lead to brighter futures and, hence, help improve neurodevelopmental outcome of preterm infants.