Fertility and Wars: The Case of World War I in France

During World War I, the birth rate in France fell by 50 percent. Why? I build a model of fertility choices where the war implies a positive probability that a wife remains alone, a partially-compensated loss of a husband's income, and a temporary decline in productivity followed by faster growth. I calibrate the model's key parameters using pre-war data. I find that it accounts for 91 percent of the decline of the birth rate. The main determinant of this result is the loss of expected income associated with the risk that a wife remains alone.