The second factor is access to birth control, most women just dont want to have children unless in very specific circumstances

Historically they were compelled

This explains the drop from 50s not the 2000s.

	▲	malicka 39 minutes ago \| parent \| next [-]
		Cell-phones. Noone’s having sex because they’d rather watch Tik-Tok; it’s got lower friction than going outside.
	▲	voxelghost an hour ago \| parent \| prev [-]
		perhaps religious and moral pressure not to excersize the choice available has decreased between 50s and 2000s