Personal trainer 4 weeks.

I got a personal trainer before I found out I was pregnant and suppose to start tomorrow. I had to pay $300 upfront and he said he does not do cancellations unless they are medical emergencies or a emergency in the family. I had a miscarriage in September at 5 weeks and now I’m pregnant again and only 4 weeks. I’m stuck between telling him I can’t go above 20 pounds with lifting or just completely not doing it bc I’m scared of another miscarriage.. thoughts????