Both events lowered the population of Europe.
Ostensibly created to limit increasing Austrian power in the Balkans, the league was actually formed at the instigation of Russia in order to expel the Turks from the Balkans. ... This dispute resulted in the Second Balkan War, against Bulgaria, in 1913 (see Balkan Wars).
10,000 - 100,000 more people
A. the workforce shifted back to men
During WWII, men went off to war while women stayed back, replacing men back home. When the men came back, women no longer needed to replace the men and their jobs.