No fetal heart. Why?

Premature rupture of membranes (PROM) is caused by infection. It is the most common cause. The female genital tract is infected by bacteria, chlamydia, mycoplasma and other pathogens. The pathogens invade the local mucosa of the internal opening of the cervix, causing the local tension of the membranes to decrease, resulting in premature rupture of membranes. If the fetus and pelvis size asymmetry or abnormal fetal position, will lead to uneven intrauterine pressure, will appear premature rupture of membranes. Fourth, fetal factors, fetal development abnormalities may also cause abortion and premature uterine contractions, causing premature rupture of membranes.