Pregnant, living with inlaws - filthy house, how to approach the subject?

Alright so me and my OH live with his mum & his sister because I'm pregnant & we can't afford our own place just yet. I'm quite a clean freak when it comes to washing hands after toilet, before preparing food etc. Just recently I've noticed that neither my MIL or my SIL wash their hands after going to the bathroom! The house in general is kept kind of tidy with an occasional hoover and tidy up, dishes put in the dishwasher but that's about as far as "cleaning" is concerned. Now I'm worried about my health and of course my unborn baby's health because surely the germs that they are spreading around are not healthy and what happens when my baby is born? I don't want them making my baby sick just because they are too lazy to wash their hands after using the bathroom! Anyone been in a similar situation or any advice on how to approach this subject without hurting my MIL's feelings as she has been very good to me on giving me a roof over my head.