Laws of Pregnancy in the Workplace

Deena
Is anyone familiar with the laws + rights of pregnancy in the workplace? I was sent home from work after being publicly embarrassed + called out because I was pregnant + told I could not return without a doctor's note. I would really like to be more familiar with my rights, + what I can do/say to stand up for myself.
In general, I think it's important for myself and others to be educated about our own rights. Am I allowed to ask for my hours to be cut down? Can I ask for my hours to be changed due to morning sickness? Can my boss refuse? I did research online, but I'm having trouble finding consistent answers.