The First World War cut short the initial phase of vigorous activity by the organized eugenics movement in France. Begun as a learned society with nearly regular monthly meetings and publication of a review, the French Eugenics Society attracted a wide range of interested parties and ideas. The society was in close touch with eugenicists in other countries, and exchanged visits with major proponents in both England and the United States. In fact, the French participation in the international movement was such that the Second International Eugenics Congress was scheduled to be held in Paris in 1915.

All of this was changed, of course, by the First World War. Meetings and publications of the French Eugenics Society were immediately suspended, and not resumed until after the war. Only occasional articles appeared on eugenics in other French journals, as the war completely absorbed the attention of the nation. The most far-reaching result of the war for eugenicists, as for most others, came from the loss of life that made the fear of depopulation an even greater concern than it had been at the turn of the century. In one sense, this heightened awareness of the population problem made people generally more open to the ideas eugenicists had talked about before the war. This is reflected in the many private initiatives begun after 1920 that, when added to the sharp increase in government involvement in everyday life that carried over from the war, blurred the distinction between private and public spheres that had made some people wary of eugenics before the war.