The baby entered the shadow realm.
Also, I doubt that's the optimal position to use a bedpan, surprised they didn't catch her right then and there; they still found out though, like how the dentists know when someone gives blowjobs.
Man, from begining to end, this manga made no sense, that's fine though, it's enjoyable, and there's always "Majime Succubus Hiiragi-san" if I want peak.
If anything, Wakaba should be the one getting the present, she's doing all the work most of the time, the mom should be glad to even get a thank you for mother's day.