Broken Limits to Birth Expectancy?

Annette Baudisch , Interdisciplinary Centre on Population Dynamics (CPop)
Ryohei Mogi, Pompeu Fabra University

A linear rise in life-expectancy over the past 180 years guides mortality researchers as a consistent benchmark to predict future lifespan. A comparable benchmark for fertility predictions is lacking. Here we reveal for period data of countries provided by the Human Fertility Database a surprisingly persistent, linear increase in the average age of childbearing over the past four decades. As driving factor, we find a linear increase in record mean age at first birth, and linear changes for record holders in age-specific fertility contributions of age groups 25-29 and 35-39, further enhanced by the general trend towards reducing higher birth orders and the persistently low fertility contributions of age groups below 25. We discuss a potential limit to the trend and suggest that these linear regularities could aid fertility forecasting methods.

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 Presented in Session 115. Novel Applications of Traditional Tools in Fertility Studies