you find yourself being lapped by infertiles.
Not just the "got married, found out they were infertile, had treatment/luck, completed their family" in the time it's taken us to have 4 non-viable pregnancies. I know there are a few of those but not too many. But more the "hadn't even met each other when Mr Spouse and I were first finding out there were problems but are now married and going through treatment". And also a few of the "almost young enough to be my own child and definitely young enough to be Mr Spouse's and have already found out they are infertile".
Yes, I have a birthday coming up. Why do you ask?