Placenta question.......

Samantha
Hello, my name is Samantha I am currently pregnant with my third and i am 16 weeks i had an ultrasound done last Thursday and the dr told me that my placenta is covering my cervix. I have never had this issue with my other kids, my questions are does the placenta move as my due date gets closer? If it does how much? If not are there exercises or yoga positions i can do to try to help it move? Or is it just going to be that way no matter what? I have never had a c section and i would like to avoid it if possible.