Sir

Rudi Westendorp and Thomas Kirkwood1 conclude that women who live longer have fewer children. This can be ascribed almost entirely to an increase in the proportion of childless women in higher age groups. For those women that have children, the mean number of children increases gradually, with a maximum in the 71-80-year-old group, followed by a slight downward trend which is not significant (Table 1).

Table 1 Relationship between age at death and number of children for married aristocratic women
Full size table

The overrepresentation of childless women in high age groups suggests that giving birth and raising children shortens life expectancy. But, once you have children, the number you have makes no difference to your life expectancy. Therefore, it is not a matter of reduced fertility, but a case of ‘to have or have not’.