[MinorityRepublican]

Here this is what I’ve found.

The countries with fertility rates around 1.5–1.7 generally have female literacy above 85–95%, while Afghanistan, Nigeria, and DR Congo have much lower female education levels, which is strongly associated with higher fertility because women tend to marry younger, have children earlier, and have fewer opportunities outside childbearing.

[Chickensoup]

So it is not fertility per se

It is willingness to procreate