Why can not I hold my pregnancies to the end?

I had my first pregnancy, which was interrupted at 24 weeks because I had no more amniotic fluid, I had a second gestation, which I had a miscarriage at + or - 16 weeks and now in 2011 I had a third gestation which was also interrupted with 24 weeks for having no more amniotic fluid. Why can not I hold my pregnancies to the end?
Expert answer:

This question is to be answered by a human reproduction specialist (if it can be answered, if there is a response), I do not know your answer, you need to look for an ultra-specialized and referral service such as a Clinic Hospital or a hospital with some university.