Because of pre-designed biologic factors, your bag of water, or amniotic sac, most often breaks spontaneously during active labor, or sometimes in early labor, when your pregnancy reaches term. It can also break prematurely before labor begins at term, or when your pregnancy is still preterm, because of factors in you or your uterus.
Factors That Cause Rupture of Membranes
Why does your water break? Although the bag of waters surrounding your baby is loosely referred to as the amniotic sac, the sac actually has two layers (the fetal membranes) holding the waters:
- The amnion is the inner layer next to the fluid and the baby.
- The chorion is the outer layer next to the inner lining of the uterus.
Both membranes rupture when your water breaks. The possible factors that cause this to happen depend on whether your pregnancy is at preterm or term, or whether your water breaks before or after labor begins.
Spontaneous Rupture at Term
At some point at term (37 weeks or after), your water has to break for your baby to come out. When your water breaks after active labor begins, this is considered normal and is called spontaneous rupture of membranes (SROM).
The factors and events involved in the rupture are not well-understood, but are a part of the pre-programmed preparation for delivery of your baby. Neonatal Principles and Practice (pages 289 to 290), notes the following factors:
- Enzymes in the amniotic membranes that get activated at the onset of labor
- Activation of prostaglandins, proteins, and other factors in the membranes
- Resulting weakening of the membranes near term, especially near the cervix
- Mechanical stress on the thin membranes from the contractions in the uterus
The biologic changes and stress weaken the collagen in the membranes causing the bag of waters to break.
Premature Rupture at Term
According MedlinePlus, premature (or pre-labor) rupture of membranes at term (PROM) refers to when your water breaks at term before the onset of true, active labor.
Why does water break prematurely at term? Based on a Global Library of Women's Medicine (GLOWN) review, the possible causes of this rupture include:
- Premature activation of the membrane enzymes, prostaglandins, and proteins
- Mechanical stress from a large baby
- Onset of pre-labor, or false labor, (Braxton Hicks) contractions
- Too much fluid in the amniotic sac (polyhydramnious)
- Too many babies in the uterus
- Bladder or kidney infection
- Vaginal, cervical, or uterine infection
Premature breaking of your waters can trigger your uterus to go into labor.
Preterm Premature Rupture of Membranes
When your water breaks before the 37th week of pregnancy this is called preterm premature rupture of membranes (PPROM), American Family Physician explains. What causes waters to break early can be based on several factors and can vary from woman to woman.
The factors that may cause your membranes to rupture too early in pregnancy include:
- Premature activation of the membrane enzymes, prostaglandins, and proteins
- Infection or inflammation in the membranes
- Too much fluid in the amniotic sac
- More than one baby in the amniotic sac
- Bladder or kidney infection
- Vaginal, cervical, or uterine infection
- Amniocentesis early in the pregnancy
- A stitch (cerclage) put in the cervix early in the pregnancy to prevent premature delivery
- Previous cone biopsy of the cervix for an abnormal Pap smear
- Poor nutrition
- Smoking
If your water breaks before your pregnancy reaches 37 weeks, this can bring on labor, and you will deliver a premature or preterm baby.
Artificial Rupture of Membranes
When your membranes do not rupture spontaneously during active labor, your doctor might decide to perform an artificial rupture of membranes (AROM). He might also rupture your membranes to bring on labor that is delayed (induction of labor), or to speed up labor that is not proceeding normally (augmentation of labor).
When Your Membranes Rupture at Home
You may experience the following if your water breaks at home:
- A sudden gush of amniotic fluid (especially if you are lying down)
- Leaking of small amounts of fluid (especially if you are standing)
- Other symptoms of a rupture
If you feel fluid leaking you may wonder if your water broke or your bladder is leaking. If you are unsure, you should go to the hospital for an evaluation, even if you are not contracting. This is even more important if you are less than 37 weeks. Your doctor will check to see if your water, in fact, broke.
Seek Medical Attention
An intact bag of waters protects your baby from harm, especially from infection. Delaying going to the hospital for medical attention after your water breaks increases the risk of infection in you or your baby or your risk of delivering a premature baby at home.
