I guess there is no single reason why people around the globe are having fewer children other than affordability. Women also have higher education. A UN Population Fund survey also cited a lack of suitable and supportive partner, expensive housing, concerns over the state of the world, paid family leave, and affordable fertility care.

But the birth rates are declining everywhere around the globe.

Here is a global comparison: https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?most_recent_value_desc=false

Or a world map: https://worldpopulationreview.com/country-rankings/birth-rate-by-country