Birth rates for the Japanese population
Some dates and figures:

In 1914, the Japanese birth rate stood at 15%, close to that of Germany or Russia, slightly lower than Java (Dutch Indies) at 22%. There was a reduction to 13.6% in 1924. For example in Japan proper there were 157 inhabitants per km?, and Hokkaido had 184 residents in per km? (cf. Java, which had 274).
In 1925, the population grew by 875,000 per year, in 1926 by 900,000, in 1927 this number grew to 1,000,000. In next last four years, the annual increase in population averaged 900,000, but in 1932-1940 the net growth was more than 1,000,000 per year, a rate which would double the population in 40 years. Japan imported 10% of the food for this population.
In 1936, Japan had 30.3 births per 1,000 residents and 17.5 deaths per 1,000. The net increase in population was 1,028,623 in 1935, but notably reduced to 653,000 in 1939 and 239,000 in 1940. Among the great countries, the birth average of Japan immediately followed British India (34.9) and was double that of the United States (16.7). This was accompanied by a growth in rice production between 1880-1940 of 60 million koku (300 million bushels).
Japanese thinkers were preoccupied with demographics: to reduce of rate of deaths and increase that of births and comparing this with growth in China and Soviet Union. Army ideologists pondered the question and produced a eugenics law which ordered the sterilization or abortion of inferior or inadequate babies and ordered the increase of birth physically "perfect" future Samurai warriors. The Japanese government gave economic support to all mothers having many children. These experts planned a ten-year program to increase the number of soldiers to the number of 100,000,000. If needed for conquest purposes, Japanese mothers "manufactured" three million babies or, in other words, a sixfold increase in this "production" by all Japanese women.
These programs were guided by Katsuko Tojo, General Tojo's wife. She said wives y should have seven children and suggested this should be the correct Japanese mother, inclusive the central government for she suggested creating one program for increasing the number of marriages