Perhaps it is time to rethink monogamy
Actually, fertility rates have fallen sharply in most Muslim countries. David P. Goldman (aka Spengler) has been writing about it for years.
https://web.archive.org/web/20090423030622/http://atimes.com/atimes/Front_Page/GH23Aa01.html
Update here: https://asiatimes.com/2005/11/statistical-evidence/
“What is killing the fertility rate in the Muslim world? There really is no such thing as a “Muslim” fertility rate, but rather a wide spectrum of fertility rates that express different degrees of modernization. Where traditional conditions prevail, characterized by high rates of illiteracy (and especially female illiteracy) the fertility rate remains at the top of the world’s rankings.”
Iran’s fertility rate fell off a cliff, which is particularly troubling and why Iran has become so dangerous.
“Iran’s fertility decline from about seven children per female in 1979 to just 1.6 in 2012 remains a conundrum to demographers. Never before in recorded history has the birth rate of a big country fallen so fast and so far. Iran’s population is aging faster than that of any other country in the world. In 2050, 30% of its people will be over 60, the same ratio as in the United States but with a tenth of America’s per capita GDP. I see no way to avoid a social catastrophe unique in human experience. Since I first drew attention to Iran’s demographic implosion a decade ago, I have heard not one suggestion as to how Iran might avert this disaster, despite some belated efforts to raise the birth rate.”
And then it got even worse:
https://asiatimes.com/2020/01/how-fragile-is-irans-regime-2/
Could a steadily declining population push Iran toward a regional confrontation?
https://asiatimes.com/2021/02/the-dangerous-disappearing-persians/
“In the Muslim countries, a man can have five wives...”
A rich man can. There aren’t that many rich men in most Muslim countries.