When they're almost ready to make an entrance or just at some point during labor, the bag pops or breaks — and amniotic fluid leaks out through the vagina. Typically, your water will break because your contractions or baby put pressure on it — like popping a balloon from the inside.

What can cause a tear in the amniotic sac?

Some causes or risk factors may be: Infections of the uterus, cervix, or vagina. Too much stretching of the amniotic sac (this may happen if there is too much fluid, or more than one baby putting pressure on the membranes) Smoking.

How does a amniotic sac rupture?

To rupture your amniotic sac, your doctor inserts a sterile plastic hook into your vagina. It may look like a long crochet hook, or it may be a smaller hook attached to the finger of a sterile glove. The hook is used to pull gently on the amniotic sac until the sac breaks. This is usually not painful.