Trends in the frequency of twin births over the last century: European comparisons

Agata V. D'Addato, Institut National d'Études Démographiques (INED) and Max Planck Institute for Demographic Research
Nadège Couvert, Institut National d'Études Démographiques (INED)
Gilles Pison, Institut National d'Études Démographiques (INED)

The evolution of twinning rate in the European countries over the last century follows broadly the same pattern, even though the total levels varied among them. Patterns and differentials in such rates across populations are described, and trends over time are given. Several complementary factors may have played a role in the similar downward and upward trends of twinning rates observed in most developed countries in the twentieth century, and some of them are discussed. In the similar pattern followed by the twinning birth rates in the European countries, one exception is the period around World War I, which represents for this reason an interesting scenario to be investigated more in detail. There has been a peak of twinning during the War or just after, but not in all countries. The twinning boom has been of different intensity and has had different timing according to the country. The communication examines which historical, biological or demographical factors may explain these differences by studying carefully demographic behavioral patterns in some countries during wartime and after, what particularly concern nuptiality and fertility, and by taking into account environmental elements as epidemics and war’s context.