Association of Gestational Age With Verbal Ability and Spatial Working Memory at Age 11

BACKGROUND: Although children born very preterm (gestation <32 weeks) have an increased risk of cognitive impairment compared with 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 to 11 years. METHODS: Cognitive ability was assessed by using the Spatial Working Memory test from the Cambridge Neuropsychological Test Automated Working Battery (n = 11 395) and British Ability Scale Verbal Similarities test (n = 11 889) in the UK Millennium Cohort Study. Each gestational group was compared with the full-term group by using differences in z scores and odds ratios for delay (scoring >= 1 SD below the mean). RESULTS: Very and moderately preterm children demonstrated significantly lower working memory scores compared with full-term children (adjusted difference -0.2 to -0.6) and were more likely to be delayed. There was no significant relationship between late-preterm or early-term birth and working memory (adjusted differences <-0.1), or between gestational age and verbal ability at 11 years. There appears to be a general attenuation in odds ratios as the child ages. CONCLUSIONS: Very preterm children exhibited working memory deficits at 11 years. However, the absence of delayed verbal skills at 11 years despite earlier delays could indicate catch-up effects.