Often, the membranes rupture (break) during labor. This is often called when the water breaks.. Sometimes the membranes break before a woman goes into labor. When the water breaks early, it is called premature rupture of membranes (PROM). Most women will go into labor on their own within 24 hours. If the water breaks before the 37th week of pregnancy, it is called preterm premature rupture of membranes (PPROM). The earlier your water breaks, the more serious it is for you and your baby.