Help for sister

A little back story she has had a few miscarriages in the early stages of pregnancy, the doctor told her she has a "hostile uterus" and then last September she lost her sweet boy at 17 weeks gestation. She just found out she is pregnant again and her doctor told her they want to put her on hormone shots while pregnant to prevent another tragedy. Any mommas have any experience with this? She's asked for my help as I'm the only one she's telling because she's too scared to tell anyone.