What have birth cohort studies asked about genetic, pre- and perinatal exposures and child and adolescent onset mental health outcomes? A systematic review
The linguistic skills of 8-year-old children born preterm (n = 42) with birthweight < 1750 grams from a 1-year birth cohort for 1985-86 in northern Finland were studied with three different language tests, namely the Illinois Test of Psycholinguistic Abilities (ITPA), the Token Test for Children (TTC) and the Morphological Test (MT) for Finnish children. Full-term control children (n = 42) with birthweight > or = 2500 grams from the same birth cohort were matched individually with their preterm pairs for age, sex, twinship, mother's education, place of residence, birth order and family type. The preterm children's language abilities were studied in relation to their neurological status and to the periventricular leukomalacia (PVL) findings of magnetic resonance imaging (MRI). The preterm children with minor neurodevelopmental dysfunctions (MND) scored worst and differed significantly from their matched controls in TTC. They also differed significantly from other preterm subgroups, namely healthy preterm and preterm children with cerebral palsy (CP), in verbal comprehension measured by TTC. PVL findings were not associated with performance in the language ability tests. A closer and regular follow-up of language development in the MND-disabled group among the low-birthweight preterm children is recommended.