It ought to be one of the biggest mysteries in social science. The standard story that it was due to “the economy” ignores that the correlation between the economy and birthrates is almost always the opposite. If it’s something specific to economic growth at that particular development stage, why don’t we see it in developing countries going through a similar stage today? If it is a result of war, why wasn’t there a similar boom after World War I? There was an uptick in the fertility rate in the years after the war, but it immediately went back on its long term decline trend.
We know that, outside France and Austria, the baby boom was due to an increase in marriage, with more people marrying and them marrying at younger ages, rather than an increase in births within married couples at a given age.(See https://www.demographic-research.org/volumes/vol38/40/38-40.pdf) Looking for areas where conditions would mimic those in the West in 1945, we should look for:
1. The economic conditions are most comparable to The U.S./Europe in the 1930s.
2. The age at first marriage is relatively high and can come down, and this, not widespread use of contraception, is the reason fertility rates are relatively low. Once couples marry they have relatively more children than married couples in the West.
3. Out-of wedlock births are low.
4. Fertility rates have been stagnant for a while.
Do these conditions apply to parts of the Arab world?