Cognitive outcomes up to age 11 years following preterm birth
While children born very preterm (gestation <32 weeks) have an increased risk of cognitive impairment compared to full-term children (39-41 weeks), the risk for children born moderately (32-33 weeks) to late preterm (34-36 weeks) and early term (37-38 weeks) is unclear. This study describes the relationship between gestational age and cognitive outcomes at 11 years and the trajectory of deficits in verbal ability from age 3-11 years. Cognitive ability was assessed using the Cambridge Neuropsychological Test Automated
Working Battery (n=11,395) and British Abilities Scale Verbal Similarities test (n=11,889) in the UK Millennium Cohort Study. Each gestational group was compared with the full-term group using differences in z-scores and odds ratios for delay (scoring ≥1 SD below the mean). ‘Persistent delay’ in verbal skills was defined as delay at ≥2 surveys at age 3-11 years.
· Late preterm and early term birth were not significantly associated with working memory or verbal ability at 11 years.
· Very and moderately preterm children demonstrated significantly lower working memory z-scores compared to full-term children (adjusted difference -0.2 to -0.6) and were more likely to be delayed, but there was no effect on verbal ability at age 11.
· The absence of delayed verbal skills at 11 years in very preterm children, despite delays at younger ages, suggests potential ‘catch-up’ effects.