Fragile cord (pregnancy)

Last week I had my ultrasound. I was 20 weeks. We are having a little boy March 19. I am so thrilled. However, the midwife told me I would have to have a second ultrasound, I need to see specialist. Apparently I have a fragile cord. It’s not attached to the placenta well. Has anyone experienced this? Any advice? I am scared to death right now, wondering what will happen. Can I do anything. Please help.