till it hurts

heard these lyrics at a restaurant:
...make babies together till it hurts... (might have been "make babies till it hurts")

and now google says there's no such song. o0

but anyway, have been thinking on "till it hurts" - what is that point?

1. you've been trying for so long the sex is bad
2. accidental pregnancy
3. you get chucked before the baby's born
4. infertility
5. spending all your money on IVF and the like
6. ending up with a gazillion babies in litter fashion
7. your adopted kid doesn't think of you as a real parent
8. morning sickness
9. miscarriage
10. bedrest
11. labour
12. incisions + stitches
13. extreme sleep deprivation
14. your arms hurt from carrying the baby
15. opposing parenting styles
16. you're not the favourite parent
17. you can't relate to the kid
18. being an absentee parent
19. suddenly they're all grown up and don't need you anymore
20. worrying that they're messing up their lives
21. locking them in their rooms
22. being lied to constantly
23. you trip on a toy and fall down the stairs
24. regretting that you had all the kids and didn't live your own life
25. divorce
26. realising you've turned into your mother/father
27. ...

endless possibilities, the mystery of a song lyric.