pesky mother in laws

Is anyone else's mother in law driving them crazy during their pregnancy? My husband and I rent an apartment my inlaws have in their basement so I will have extra help with the baby. Every day she has a comment about how big my bump is, how much weight I'm gaining, and she just judges me for every ounce of uncomfortability I have. I have only gained 3 pounds over when I'm supposed to but I quit smoking as soon as I found out I was pregnant and I think that has to do with the weight gain. How do I politely tell her than I don't care about her opinion on my pregnancy? She has had 5 children and compairs her to me all the time.