Can a pregnant worker be laid off ?

I am 31 wks pregnant now. I am employed with my current employer for more than 2 yrs now. I worked for a group for the first 20 months in a group where I got good reviews on my performance. About 6 months ago before I announced my pregnancy, I was assigned to a different group which I found it very unfriendly. I am finding the entire team including manager not trusting me about performance. However, I heard this feedback after I announced my pregnancy. This manager talked to me about some of the issues. I explained him about some of my concerns about other team members. Since then I have not heard any more feedbacks. But my situation with team members is getting worse. This group hired after hearing a very positive feedback from my previous group. Now my company is going through a big layoffs. I am thinking I may be a part of it. They may try to say that my performance was not good. They have enough proof to prove my performance has been affected. But it is the same situation with other team members as well. It is just my mistakes that comes and gets documented and not others' mistakes. If they lay me off based on performance reasons, how can I prove that it is a discriminatory act ?