I had my second baby during my midwifery program - I even missed a final because I was giving birth

I had no problems whatsoever finishing. The school helped as much as possible - I even pumped during clinicals.
Does your school have an ombuds office? My school had one - they act as neutral mediators in disputes and make sure the school policies are being followed. I would doubt an official policy about pregnancy exists because of the legal liability, it's probably just someone's preference. An ombudsman might be able to help you find out what your rights really are.
Becki