The spread of economic and cultural information through internal migration is more effective in reducing birth rates than industrialisation or education. This is the conclusion of new research published in the May 2019 edition of The Economic Journal which looks at the convergence of birth rates across French regions in the 19th Century.


The study by Guillaume Daudin, Raphaël Franck and Hillel Rapoport suggests that reaching sustainable population levels today may depend more on the flow of information and people rather than economic development.


They argue that migration by itself causes fertility differences to fade. Their research finds that 80% of the reduction in fertility in France from 1861-1911 can be attributed to migration rather than other economic or demographic factors.


France was one of the first countries where birth rates declined despite its lacklustre economic performance during the 19th Century. While rates started to fall in the late 18th Century, it was only in the second half of the 19th Century that fertility rates across French regions began to converge (see figure 1).


Figure 1: The Puzzle. Why did France fertility converge to a low level?*

figure 1.png

The authors suggest that this is because of the diffusion of economic and cultural information through rising internal migration. This spread information, preferences and beliefs about fertility to different regions and contributed to new behaviours.


For example, information on social norms around family sizes in Paris may have been taken into account by those who had stayed behind who might want to emigrate in the future or emulate Parisian ideas. Or it could have been grounded in an economic idea based on the cost of raising children in urban areas, especially Paris. The researchers show that this was more effective in reducing fertility than social or economic factors, like urbanisation, industrialisation or increased schooling.


The researchers use both census data and the “Survey of the 3000 families” conducted by Institut National d’Études Démographiques (INED) to measure migration. They use variation in transportation costs, resulting from the gradual construction of railways, to remove variation linked to demographic changes. They show that when people emigrated towards a low fertility region (such as Paris), their old region experienced a reduction in fertility. Similarly, when a region received more immigrants from a low-fertility region, it experienced a reduction in its own fertility.


Can internal migration foster the convergence in regional fertility rates? Evidence from nineteen century France by Guillaume Daudin, Raphaël Franck and Rapoport is published in the May 2019 issue of The Economic Journal.


*The Coale Fertility Index is the ratio between the actual number of births and the expected level of birth if the population had the same fertility level as the Hutterites, a strict religious group in Northern America with a very high level of fertility. It hence controls for the age structure of the female population.


Sources : French data Bonneuil, N. (1997). Transformation of the French Demographic Landscape, 1806-1906. Oxford: Clarendon Press and our own computations for 1911. English data : Princeton Project on the Decline of Fertility in Europe.


Guillaume Daudin

Professor of Economics at Université Paris-Dauphine & OFCE

Raphaël Franck

Senior Lecturer at Hebrew University of Jerusalem

Hillel Rapoport

Professor at Paris School of Economics