But that is not the end of the story. While Turkey's fertility rate as a whole is falling, the Kurdish minority of Turkey (currently 15 per cent of the population) has such a high birth rate that some (not the least of which is Prime Minister Erdogan) believe that they could become the majority in Turkey within two generations
It has become common to hear conservatives panicking about the idea of Muslims supplanting Christians due to an higher birthrate. Here is an article about fears of one Muslim ethnic group being supplanted by another with an higher birthrate. I suspect that such fears are misplaced and in the long-term, the ethnic Turk and Kurdish birthrates will even out. Yet this does demonstrate that their is no automatic rule that Muslims have lots of children. Their are a whole bunch of economic factors that affect fertility aside from religion.