The evolution of mean paternal age in a long perspective – are today’s fathers really older than back in the days?

Kai Willfuehr, Max-Planck Institute for Demographic Research
Sebastian Klüsener, Max-Planck Institute for Demographic Research

There is strong evidence that advanced paternal age at childbirth is associated with detrimental outcomes in historical as well as in contemporary populations. Some studies indicate that mean paternal age has increased substantially over the last decades. Given the increases in mean paternal age in recent decades and the detrimental outcomes associated with it, this is an important issue for public health. However, there are only few studies which focused on paternal age at childbirth. Direct information on mean paternal age is for instance available for England and Wales 1964-2013; France 1899-2005 and Belgium 1939-1995. In most databases, reliable information on mean paternal age is missing. However, since fathers tend to be on average two to three years older than mothers, mean paternal age at childbirth can be estimated more or less accurately from mean maternal age. The relationship between maternal and paternal age appears to be robust in historical as well as in contemporary European populations, and is also reflected by the gap in male and female age at first marriage. We therefore calculate mean paternal age at childbirth by mean maternal age plus the difference between male and female age at first marriage. The reliability of this method is tested empirically using the datasets where maternal and paternal ages are recorded. Datasets and collections where mean paternal age at childbirth can be estimated from maternal age are for instance available at IPUMS International and the European Historical Population Samples Network. Our results indicate that mean paternal (as well as maternal) age around 1900 was substantial higher than current levels and that today’s paternal age level is comparable with that in the 1920s.