Association of Apgar score and postterm delivery with neurologic morbidity: Cohort studies using data from Danish population registries

Antenatal and perinatal events are important for neurologic development, but the mechanisms involved are not fully understood. The three thesis studies examined the association of perinatal characteristics with subsequent neurologic outcomes by record linkage of birth data with medical and administrative population databases in Denmark. Study 1 and Study 2 sought to determine whether 5-minute Apgar score is associated with subsequent neurologic morbidity after accounting for its known determinants. In a cohort of >130,000 singleton births, neonates with an Apgar score <7 had 2- to 5-fold greater risk of epilepsy hospitalization before age 12 than did neonates with a 5-minute Apgar score ≥7. Study 2, based on examination of draft records of >17,000 Danish men, showed that 5-minute Apgar <7 score was weakly associated with worse intelligence test performance and worse sensory acuity. Study 3 examined the association of postterm (≥42 weeks) delivery with the risk of childhood epilepsy in a cohort of >250,000 live singleton births. Postterm delivery was found to be a risk factor for epilepsy with onset during the first year of life. We estimated a 1.2- to 2-fold increase in risk and a stronger effect was conferred by longer gestation. An enhanced effect was also found for neonates delivered with forceps or vacuum or by cesarean section. This was one of the first large cohort studies to explore long-term neurologic consequences of postterm delivery. All three studies point to an important role of prenatal and early neonatal period in neurologic development. Studies 1 and 2 suggest that antenatal and perinatal conditions set the stage for neurologic dysfunction or affect future susceptibility, while Study 3 offers a new insight in long-term repercussions of prolonged intrauterine stay.