I have been told that if I step down from my position they do not have a job for me and we will have to part ways - the management position is too much stress on me and would like to go back to my original job before I was pregnant. I have had no training in the management position and it was given to me because the last person left and was told to do my best and make mistakes to learn from. I need some help - is this legal?

They have no requirement to give you an old job or change your jobs.