I was on a flight recently and a woman tried to use the bathroom as the plane was preparing to land. She was told to sit down and she effed and blinded and ranted and raved. I felt bad for her but I also didn't understand her surprise that she wasn't allowed to use the bathroom as the flight was descending. Surely everyone knows that? Disappointed yes, but that level of entitlement was quite shocking.
Anyway, I digress. I always knew, from my teens, that I had a biological clock and it would start it's descent around my mid thirties. Anytime I read about a woman of more advanced years having a baby, I knew that it was most likely due to some kind of scientific intervention. Most 50 year old women won't find themselves pregnant through natural means. Even as a 16 year old reading Just Seventeen, I knew that this was an anomaly. I understood, even then, that these kinds of pregnancies are often the result of money and privilege.
At 38, my husband suggested we have our third baby. I told him we could try but it probably wouldn't work as my fertility had most likely declined a lot since we last had a baby. I wasn't expecting to get pregnant but BOOM!, was looking at 2 lines on a pregnancy test 2 months later. Everything was fine, so it can work out.
However it's important to accept the limitations as probable and hope for the best, rather than expect to fall pregnant naturally late into your 40s and feel crushed when it doesn't happen.