Why do I always seem to argue with my mother while I am pregnant?

Every time I am pregnant my mother and I butt heads almost constantly. She is 100% a narcissist and when I am not pregnant I seem to tolerate it so much easier. This time around she has no idea I am pregnant and we are still feuding. I don’t know if it is me or her. She turns everything I say into an “attack” against her. This causes me to have an attitude and get super annoyed and angry which escalates everything. She NEVER apologizes and brings me to tears all the time. She thinks I am disrespectful even though I do so much for her. I would love some advice on how to deal.