Lifetime Reproduction: Mean, Variance, and Other Statistics across the Fertility Transition

Silke van Daalen, University of Amsterdam
Hal Caswell, University of Amsterdam

Lifetime reproductive output (LRO) is the total number of children a female produces over her lifetime. Unlike total fertility rate, the LRO includes effects of mortality. The mean, variance, skewness, and other statistical properties of LRO can be calculated from a Markov chain model and age-specific mortality and fertility. The variance in LRO represents the individual stochasticity implied by the fertility and mortality schedules. We applied this method to period data from 40 developed countries from 1891 to 2011, and from two hunter-gatherer populations and from Hutterites, as examples of populations without fertility control. We present the statistics of remaining lifetime reproduction by age, the changes of those statistics across the fertility transition (from 1965 to 2010), and their relationship to the Human Development Index (HDI). We explore relationships among the statistics, and find that mean and variance of LRO have converged to an apparently universal trajectory over time.