Japan is leading the way in a crisis of population collapse. Japan had peak woman about 53 years ago in 1970. This was also about the time they had peak children.
During Japan's first postwar baby boom (1947–49), there were 2.5 million births a year. In the second baby boom (1971–74), there were 2 million annual births.
Japan Could Be a Vulnerable Population by 2050
Japan's population peaked in 2008. By the time Japan's overall population peaked, the number of fertile women had fallen in half. The total fertility in 1974. The number of fertile women is dropping and the number of babies each is having is dropping. Japan is now at less than one-third of its peak baby years.