Legal Question in Employment Law in California

It is only unlawful for the company to reduce your hours and take away your benefits BECAUSE you are pregnant. If the same decision would have been made in the context of company layoffs and salary reductions regardless of whether you are pregnant, then this is not unlawful.

Your pregnancy does not protect you from general business changes and layoffs, as long as they are not made against you 'because of' your pregnancy, a claim which you would have to prove. If you were the only one laid off, that would be highly suspicious at least, but you said the company was doing this to others as well. You should be negotiating with the company to retain your hours and/or benefits. Simply raising the issue and gently questioning why you were selected, would discretely alert them to the 'risk' they bear if you made a pregnancy discrimination claim, and might get them to keep you in a position with benefits.