i know what you mean.... when i was a student and shared a house with three others i seemed to be the only one who knew the meaning of the words "clean" and "tidy". it was awful and nearly drove me mad! and i wasn't pregnant then! i ended up more or less moving in with my OH just kept my things in my room and came back only if i needed to pick something up as i literally felt sick when i saw (and smelt) the state of the house. i ended up gradually just moving all my stuff into OH's house, which was also a shared house, so we literally lived in one room!
when we were about to move out after finishing uni they wanted me to pay equal shares of all the bills (water, gas, electricity, phone, tv licence and all that) and i basically told them where to stuff it as because of their mess i had hardly been there at all for over 6 months, hence had not really used any of the facilities. they were pissed off at me for that but i said i'd leave them £20 for everything, just to cover any costs i had incurred during my visits to pick up my stuff. at the end of the day i paid towards the bills at OH's place as i thought it only fair since i was practically living there.
when i finished uni, me and OH shared that room for about 6 months whilst we looked for a house to buy. it was BLISS when we moved into our own house! and i'm the first to admit my house is not always spotless, but at least it's clean, and tidy most of the time!
i'd dump all of their stuff in one big cardboard box, clean my own stuff and keep it in my room. don't they realise there's gonna be a baby in the house soon, and that SOME level of hygiene is important?! imagine if your LO got a nasty bug from the bacteria that grow in the mess thay leave around.... is there no way you could get out of that house and get even a little studio flat of your own?