The association between cord pH at birth and intellectual function in childhood

BackgroundAcidemia at birth is very common but little is known about its long-term consequences.AimTo determine if pH at birth is related to established tests of intellectual function.SubjectsSchool children aged 6–8, for whom obstetric data were available, who had been delivered after labour at term, and had an umbilical cord arterial pH > 7.00 (i.e. that was not extremely acidemic).Study design/outcomesRetrospective cohort study correlating birth and arterial pH data with childhood tests for non-verbal intelligence, grammar comprehension and literacy.MethodsRelationships between pH and cognitive measures were analysed with parametric correlations. Partial correlations were used to examine these relationships, controlling for possible confounding factors.ResultsArterial pH was significantly negatively correlated with literacy (p = 0.001) and with non-verbal intelligence (p = 0.033).ConclusionsLower arterial pH is associated with higher scores on literacy and non-verbal intelligence tests at ages 6–8. This is unlikely to be a chance finding and is further evidence that acidemia in isolation should not be considered an adverse outcome. Further research on the relationship between labour and long-term cognitive measures is required.