Ah, so very very sorry. Second trimester miscarriages are so very painful emotionally! The term for this is PPROM. It's not always clear why it happens but one reason may be an infection of the membranes. Smoking is a risk factor for this as is having an std. They may also want to check your cervix. You weren't far enough along for this to usually be the case but it still should be checked, if you had an incompetent cervix which can thin and then membranes rupture. So, I'd talk to your doctor more about this. I am hoping they will give you the news that this is a one time scenario. I do know a friend that this happened to who had another baby not long after that went full term. So, hang in there. hugs