Sometimes malformations of the uterus or cervix are associated with early delivery. Often these are unknown to the woman prior to becoming pregnant. Even if known, how much a uterine fibroid or unusually shaped uterus will affect the pregnancy is often difficult to predict. It is not known why the fetal membranes rupture too early in some pregnancies. When the fluid around the baby leaks out, the baby and mother are exposed to infection.
Labor usually occurs within a few days.
Babies born too early face significant problems, and infection makes the situation worse. Infections of the vagina, cervix, or uterus have been studied as possible causes of preterm rupture of the membranes. When infection is present in the vagina or cervix, toxins produced by the organism may weaken the membranes, making them more likely to leak or rupture. Inflammation from infections causes a local release of a substance known as prostaglandin. Prostaglandins are found throughout the body, and the substance is believed to have some role in the beginning of labor.