What do I do?

Becca
Okay so my best friend/cousin and I are 16 and she lost her virginity when she was 14. However she has a boyfriend that she obviously does stuff with and the other day she told me she had a miscarriage but after all of this she still hasn't told her mom and she is not on the pill and doesn't always use condoms. This has been an ongoing occurrence now so what should I do as a friend without upsetting her?