how to comfort a friend after a miscarriage

My best friend got pregnant super quick for her first child last year. A few months ago she told me she and her husband were trying to get pregnany again but she had a miscarriage at 6 weeks. She was upset but was getting past it but today she told me she had another miscarriage. I don't know how to comfort her anymore. I have no idea what to say because I don't know what that's like but I also don't know what to say because I don't want kids. Can anyone tell me how to help her through this?