Well I'm not a woman, so I don't have direct experience. But I think that young girls, for example, are frequently told in school and at home that they can be anything they want, doctors, lawyers, scientists, etc. and that is great, but I think very little is said about being a mother and their biological clock and the tradeoffs that entails, or if it is addressed it is sort of glossed over with a "you
can have it all" message.
So girls grow up with a career-oriented mindset, and don't do any careful thinking about what they want, or think about kids/family as something they will do "later" or "when I'm ready" and before they know it they find themselves at 35 years old and unable to get pregnant.