If you realy need to build more rooms, you can modify HTML file.14 "guests" + 6 children = no more room in the guest house. It won't let me build additional rooms in the workshop. Problem will only get worse as my "guests" give birth.
Personally I find the "real-time" pregnancy term refreshing -- too many games shatter the immersion by cutting it short, so please don't change that.
Just open file with any text editor and ctrl+f:
guesthouse_cell - for guest beds,
basement_cell - for basement cells.
Under those lines will be "show:" line like
guesthouse_cell: {
show: ($game.location.guesthouse ?? false) && ($guesthouseLimit ?? 3) < 20
just change number after < to any number you want and save changes, for example:
show: ($game.location.guesthouse ?? false) && ($guesthouseLimit ?? 3) < 200