And there's the issue of taking care of the child afterwards. Perhaps there are (possibly expensive) ways to magically speed up pregnancies so that it doesn't leave characters knitting baby clothes for nine (ish) months, and maybe there's either a good adoption or daycare system in place, or maybe a deal with monsters to let them have their children sent to them to raise, since it's already been stated that monsters and player races have made deals not too dissimilar to this (no killing, female adventurers to rape.)