It's to highlight something fucked up that's sometimes done on women after giving birth.

Quoting another comment in the thread:

the Husband Stitch is a real thing that used to be pretty commonly done regardless of what the woman wanted and often without her foreknowledge or consent. It’s an extra stitch or two placed when sewing a woman back up after a vaginal tear or episiotomy during labor. The purpose is to make the woman “tighter” so her husband can still enjoy having sex with her even though she’s given birth, which is staggeringly misogynistic and cruel. And it usually results in really painful sex for the woman because her vaginal opening is artificially small plus now it has inflexible scar tissue.