Here is the age pyramid of German population in 1950. The effect of the first war is very clear, the number of children plummeted in 1915. However, the 1940-1944 cohort is more numerous than either the previous or the following ones. Why?

EDIT: As u/QCrimson pointed out, the said cohort was actually the 1936-1940 one, so my question does not make sense.