Early Life Conditions and Later Sex Differences in Adult Lifespan

In this study we tested our hypothesis (and preliminary observations) that early-life conditions may determine in part the later sex differences in adult lifespan. We found that such variables as (1) father's age at person's conception, (2) parental lifespan, and (3) month of birth, have larger effects on adult lifespan (life expectancy at age 30) in females rather than males. Daughters born to particularly young fathers (below 25 years) or old fathers (above 45 years) live shorter lives, while sons are less affected by paternal age at conception. The response of progeny lifespan to exceptional parental longevity (lifespan above age 90) is particularly strong for female sex of the progeny. Women born in May or December live longer compared to those born in February, while male lifespan is less affected by the season of birth. Large family size (11+ siblings) increases daughter's lifespan, but decreases son's lifespan, thereby increasing the gender lifespan gap. These findings are confirmed through multivariate analysis of lifespan and hazard rates taking into account more than 20 predictor variables (including simultaneous consideration of such closely related variables as birth order, sibship size, parental ages at person's birth) as well as observed interfamilial differences and unobserved familial heterogeneity (through multilevel modeling).