Rupture of membranes (ROM) or amniorrhexis is a term used during pregnancy to describe a rupture of the amniotic sac. Normally, it occurs spontaneously at full term either during or at the beginning of labor. Rupture of the membranes is known colloquially as "breaking the water" or as one's "water breaking." A premature rupture of membranes (PROM) is a rupture of the amnion that occurs prior to the onset of labor. This typically occurs before the pregnancy's 37 week gestation. In the United States, more than 120,000 pregnancies per year are affected by a premature rupture of membranes, which is the cause of about one third of preterm deliveries. Sometimes, a child is born with no rupture of the amniotic sac (no rupture of membranes). In such cases, the child may still be entirely within the sac once born; such a birth is known as an en-caul birth. Effects When the amniotic sac ruptures, production of prostaglandins increases and the cushioning between the fetus and uterus is decreased, both of which are processes that increase the frequency and intensity of uterine contractions. On occasion, with the rupture of membranes, particularly if the head is not engaged, the umbilical cord may prolapse. A cord prolapse is an obstetrical emergency, as the descending head may block fetal-placental circulation. Once the membranes are ruptured, bacteria may ascend and could lead to amnionitis and fetal infection. A premature rupture of membranes can have multiple effects on the fetus such as increasing their risk of prematurity and facing neonatal or perinatal complications. Types SROM: spontaneous rupture of membranes. This term describes the normal, spontaneous rupture of the membranes at full term. The rupture is usually at the bottom of the uterus, over the cervix, causing a gush of fluid. This gush may be quite small (such as 50ml), or it can be significantly large (200-300ml) depending upon amount of fluid in the amniotic sac, and to what extent the fetal head is plugging the hole and retaining fluid in the sac. A spontaneous rupture that occurs early in labor may actually be related to other complications resulting in delayed labor. These complications may include a contracted pelvis, breech presentation, or occipito-posterior position. PROM: premature rupture of membranes. This term describes a rupture of the membranes that occurs before the onset of labor. PPROM: preterm, premature rupture of membranes. This term describes a rupture of the