Dress code for Pregnant women

My husband made a reservation for 3 people which included myself, my 8 year old son and my husband. We arrived there I was told I'm not allowed to enter the restaurant because I'm wearing a trucksuits. I'm a pregnant woman, it's was a cold night. I explained to the manager that this is what's comfortable for me in this state, mind you the manager was a woman. Out of all the people she should understand the state I am in.I cannot wear jeans because they are uncomfortable on my abdomin nor a dresses on a cold night. I was looked at like I was crazy. I would like to know since there is strict rules on dress code what is the dress code for pregnant or people with disabilities should wear?! I ended up having dinner away from my family because of the cheeky and rude manager