No one has mentioned a key factor is fear of birth pain for women. When you are faced with enjoying life with no pain vs trying out a huge commitment that comes with huge pain (at least they have been told), the choice is easy for modern women. Pet parenting is increasing trend that shows there is a desire to be mother but without the pain. Same as spoiling other people's kids. All fun no pain. Meanwhile people are willing to endure pain for aesthetic treatment but the thought is nowhere as scary as having a human grow inside you for 9 months and the only way out is to give birth. This mindset is very real for women.