Growth after preterm birth and cognitive functioning and mental health in adulthood

Background: Preterm birth (before 37 weeks of gestation) is a major cause of infant mortality and morbidity worldwide, and preventing its burden is a health care priority. Even in adulthood, individuals who were born preterm perform, on average, worse on tests of cognitive functioning than term-born peers do, and may have more mental health problems. Early growth failure is common among preterm individuals, and some studies have suggested that those preterm individuals who grow poorly in infancy have more neurodevelopmental problems later on in childhood. It is unclear whether these associations persist into adulthood and whether they extend beyond the smallest and most immature of preterm infants, to the majority of preterm infants who are born late preterm (at 34-36 completed weeks of gestation). It also remains unknown whether early postnatal growth patterns predict mental health outcomes - some partly conflicting evidence suggests that intrauterine growth restriction at least associates with mental health problems. The mechanisms explaining the associations between growth and neurodevelopment are also unclear. Early growth reflects a number of intertwined early-life environmental factors and individual characteristics, and while altering neonatal nutrition can affect growth, it is not known whether changes in nutrition can improve long-term neurodevelopmental outcomes. It has even been suggested that faster growth and higher nutritional intakes during the early postnatal period can present a trade-off between improved neurodevelopment and increased cardiovascular risk. Methods: The 157 participants of the Helsinki Study of Very Low Birth Weight Adults (HeSVA, birth weight