I'm a little tired of hearing people confuse a dropping birthrate with increasing childlessness. They are not the same thing. And hearing that it's education and economic freedom that lead to childlessness.
Historically, in lots of places and at various times, childlessness among women has been higher than it is now.
Because of poverty. Because of a lack of men (wars). Because of a lack of health care. And for (probably) the same number as today, a lack of interest among a fairly small cohort of women.
In some places, and at various times, *lower* education and incomes have been more closely associated with childlessness. This the case right now in some places.
Because kids are expensive. Because women with low incomes and poor education are more likely to have been (historically and now in some places) working in other people's houses and unable to marry. Because poorer women can't access IVF and other fertility care. Because poorer men are more likely to be in military service or incarcerated.