A bulging bag in pregnancy refers to the amniotic sac bulging out through the cervix. This can happen when the amniotic sac is under pressure from the babys head or contractions. It is not a cause for concern and is a normal part of the birthing process. However, it can increase the risk of the amniotic sac rupturing prematurely, which can lead to complications such as infection. If the amniotic sac ruptures before the onset of labor, it is called premature rupture of membranes (PROM) . If the amniotic sac ruptures after the onset of labor, it is called spontaneous rupture of membranes (SROM) . If the amniotic sac ruptures before 37 weeks, it is called preterm premature rupture of membranes (pPROM) .