That is hardly a reason. People used to starve and had tens of children. Why dont we just accept that is cultural?

Since then we have invented much more reliable methods of birth control and have managed to bring infant mortality way down.

Culture meaning women having economic freedom, physical security, and access to birth control?

Women don't have "tens" of children due to culture, they have them due to not having an option. The data says they (as a global group) barely want 2 or 3 (which makes sense to those that have seen the risks and tribulations).