Holiday plans

Due end of Dec and told both our families we were not planning to do anything over Christmas and obviously need to play it by ear since we don't know when baby will be here. We pretty much told families to go ahead and make their plans and not to expect us. Well, my parents seem to think this does not apply to them. So my mom told me they are coming over to our house on Christmas, whether I'm still pregnant or have just had the baby. I did not invite them over, I did not intend on making plans to spend the holiday with anyone except my husband. We do not plan on cooking or cleaning or hosting house guests. I purposely traveled home to see them for thanksgiving because of not planning to see anyone for Christmas. I am grateful they want to see us then but I'm feeling like our wishes are not being respected.

Anyone else dealing with families not respecting boundaries when due around the holiday? How do I tactfully set and enforce our boundaries?