Nobody's feed

I mainly read BL, and when I’m not reading BL, I’m reading some slice-of -life vanilla story, so I don’t really read too much straight smut.
I see comments all the time in BL about people wanting the bottom to get pregnant.
Does that happen in straight smut as well? Are the readers clamoring in the comments for the women to get pregnant?
I’m just curious if it’s a smut thing, or a BL thing.