Is a reversal of the low fertility rate a universal phenomenon? - evolutionary approach

An empirical relation indicates that an increase of living standard decreases the total fertility rate (TFR) but this was broken in highly developed countries in 2005. The reversal of the TFR was associated with the continuous economic and social development expressed by the Human development index (HDI). We have investigated how universal and persistent is the TFR reversal. The results show that in highly developed countries, $\mathrm{HDI}>0.85$, the TFR and the HDI are not correlated in 2010-2014. Detailed analyses of correlations and differences of the TFR and the HDI indicate a decrease of the TFR if the HDI increases. It is useful to consider the population to be a living and complex system that interacts with the environment, then we can better understand a transient nature of the TFR reversal. In these systems a response of the TFR on economic, social, and political changes could be permanent, transient, and random. Our results show a transient character of the TFR reversal. We believe that knowledge of the fundamental nature of the TFR is very important for a survival of highly developed societies.