Is later better or worse? Advanced parental ages and offspring IQ, health, and mortality

ABSTRACT : Advanced parental ages are associated with a range of negative outcomes for the adult offspring, such as decreased health, cognitive ability, and life expectancy. The interpretation of these associations often relies on parental reproductive aging. We use large population-based samples from the U.S. and Sweden to analyze how alternative mechanisms - social selection, age at which the children lose their parents and improving macro conditions - influence the link between parental ages and offspring outcomes. Consistent with prior work, we find that children born to mothers or fathers aged 35 years or above have worse IQ, health, and mortality outcomes than those born to parents aged 25-34 years. These associations are to large extent explained by observed and unobserved parental characteristics and by early parental loss, though for some outcomes small negative effects remain net of these controls. However, these negative effects are more than offset by improving macro conditions: comparison of siblings reveals that due to secular positive trends in health over cohorts, postponing parenthood up to advanced ages results in taller children who score higher in cognitive ability tests and have a decreased risk of death, despite the negative parental age effects.