They are supposed to auto-deflate at night, except for due to pregnancies, but that seems to only partially trigger due to the option for them to want to keep it in to get pregnant. Eventually I intend for it to be enforced via Rules (keep it in/wash), conversations (Release it), or items (plugging it up).
That’s still pending though. Hopefully v.07 will fix a lot of the larger issues with inflation not resetting or occurring too sporadically and the extra features will resolve the rest.