Abstract
About 80% of premature (< 37 gestational weeks) infants have been born moderately preterm (32+0-33+6 weeks) and late preterm (34+0-36+6 weeks). Very preterm birth (<32 weeks) is a well-known risk factor for adverse neurodevelopmental outcome, but the risks concerning moderately and late preterm infants have earlier been underestimated. Lately, concern about later neurodevelopmental impairments among these children has been emerged. Our project was to undertake a national register study on the incidence and risk factors of sensory impairments, cerebral palsy (CP) and intellectual disabilities (ID). The aim of this review article is to provide a summary of our work and earlier publications on this topic.
Our study comprised all children (N= 1039263) born alive in Finland in 1991-2008. After exclusions (missing data on gestational age (N=5520), major congenital malformations (N= 13007) and death before the age of one year (N=2659) the population consisted of 1018256 children, who were followed up to the age of seven years or up to 2009. They were divided into four groups as follows: very preterm (N= 6329), moderately preterm (N=6796), late preterm (N= 39928) and term (N=965203). Incidences of sensory impairments, CP and ID (intellectual quotient ≤ 70) were explored by linking health register data. Antenatal, birth-related and neonatal predictors of disabilities were established by multivariate analysis.
The incidences of sensory impairments, CP and ID decreased with increasing gestational age. Compared with term birth, moderately and late preterm births were significantly associated with the risk of visual disturbances, blindness and CP. Late preterm birth predicted a risk of hearing loss. Preterm birth seemed not to be associated with an increased risk of intellectual disability. The most significant predictors of neurodevelopmental disabilities among moderately and late preterm born children included one-minute Apgar score < 7, intracranial hemorrhage, male sex, small for gestational age, smoking during pregnancy and early antibiotic treatment. These results are mostly in accordance with other reports on the outcome of moderately and late preterm born children.
In conclusion, moderately and late preterm born children seemed to be at an increased risk of sensory impairments and cerebral palsy, but not intellectual disability.