Everybody who pays attention to these sorts of things knows Muslim societies are almost uniquely immune to the forces that have been driving down fertility rates on every continent for decades. But everybody, it seems, fell asleep before the final act.
Throughout the ummah (the Arabic term for the global Muslim community), the average number of children born to women is falling dramatically. (Apoorva Shah and I examine the evidence in detail here.) According to the UN's Population Division, all Muslim-majority countries and territories witnessed fertility declines over the past three decades. To be sure, in some extremely high-fertility countries of sub-Saharan Africa (think Sierra Leone, Mali, Somalia, and Niger), declines have been modest. And in the handful of Muslim countries where a fertility transition had already brought childbearing down to around three births per woman by the late 1970s (think Soviet Kazakhstan), subsequent declines have also been limited. But in the great majority of the rest, declines in the total fertility rate have been jaw-dropping.
Indeed, as Table I shows, six of the ten largest declines in fertility in absolute terms for a 20-year decade period in the postwar era have occurred in Muslim-majority countries. What's more, four of the six are Arab countries, while five of the six are in the Middle East. No other region of the world comes close in the sheer speed of its transition.
Table 2 offers another way to look at this demographic revolution. Again, we rank the top-ten fertility declines for a 20-year period since World War II. But here, the rankings follow percentage declines rather than absolute declines. By this metric, "only" four of the top ten (and two of the top four) were Muslim-majority countries. But all countries on this list count as Olympic-class sprinters in the reverse-fertility race, all recording declines exceeding 63 percent. Much of the ummah now has fertility rates comparable to affluent non-Muslim populations in the West.