Fertility: Transitions and Measures

Childbearing, or the fertility of human populations, has changed profoundly in the last several centuries. Four aspects are basic for measuring and studying human fertility:age,parity(number of children ever born), length ofbirth interval, andpopulation reproductivity. Additionally, there are cross‐cutting issues of time perspective and of fertility dimensions. The variety of fertility measures at a given time is both a result of the data available and a precondition to expansions in data collection efforts.