BackgroundFactors early in life, even prenatally, could affect subsequent health and development of disease. Studies have consistently shown a small but significant correlation between birthweight in the normal range and childhood cognitive ability. However, only two studies have investigated whether this correlation persists into older age, showing no significant effect. The aim of this investigation was to assess whether factors early in life (birthweight, gestational age, parity, antenatal complications, neonatal complications, and social group), affect cognition in childhood and whether these effects persist.