Childbearing rates are declining worldwide. Sub-Saharan Africa has the highest fertility rates of any region;
for instance, in Nigeria, a woman gives birth to an average of 6.0 children over her lifetime.
Moderate rates of
fertility are found in the Middle East, while the Americas and Oceania have levels of fertility that are sufficient
to replace, but not expand, a country’s population in the next generation (about 2.1). Below-replacement-level
fertility is widespread in East Asia and Europe