Premature rupture of membranes (PROM) is the breaking of the amniotic sac before labor begins. The sac contains amniotic fluid and the developing baby. With PROM, the amniotic fluid inside the sac leaks or gushes out of the vagina. This is also known as your water breaking.

Fetus with Amniotic Sac

© 2009 Nucleus Medical Media, Inc.

PROM occurs during the third trimester after 37 weeks of gestation. A related condition called preterm premature rupture of membranes (PPROM) occurs before 37 weeks of gestation.

PROM increases the risks of certain pregnancy complications, including:

Call your doctor right away if you suspect that your water has broken.


The causes of PROM are not clearly understood. Some of the possible causes are:

  • Early dilation of the cervix (may be due to the weight of baby and placenta, or changes in the cervix itself)
  • Infections of the vagina, uterus, or membranes surrounding the fetus

Risk Factors

The following factors may increase your chance of PROM:

  • PROM in earlier pregnancies
  • Infection in the amniotic sac
  • Other infections in mother (eg, chlamydia)
  • Bleeding during the second and third trimester
  • Amniocentesis
  • Certain procedures used to treat abnormal conditions of the cervix (eg, cervical conization)
  • Lung disease during pregnancy
  • Connective tissue disease
  • Nutritional deficits
  • Low body mass index
  • Smoking during pregnancy


The main symptom of PROM is fluid leaking from the vagina. You may experience a sudden gush of fluid or a slow, constant trickle. It can be difficult to distinguish between a slow amniotic trickle or urine. Your doctor can do simple tests to determine this.

PROM also increases the risk of infection. Symptoms include a fever above 100.4ºF (38ºC). If you have any of these symptoms, call your doctor right away.


If a large amount of fluid is leaking from the vagina, diagnosing PROM can be straightforward. To confirm the diagnosis, the doctor may do the following tests:

  • Visual exam—the doctor may be able to see a trickle of fluid through the cervix, or a pool of fluid collected behind the cervix
  • A nitrazine paper test—the doctor puts a small amount of fluid on a piece of paper to see if it is amniotic fluid
  • Look at the fluid under a microscope to see if it is amniotic fluid

The doctor will also check you for fever and other signs of infection. He will monitor your baby for any signs of distress.


Treatment of PROM depends on when it occurs in the pregnancy. If it is close to your due date, you and your baby will be watched closely. For example, your baby’s heart rate will be monitored.

Labor usually begins within 24 hours after PROM. If labor does not begin soon after your water breaks, the risk of infection increases. In many cases, labor will be induced by giving you medicines. Antibiotics may also be given.


Researchers are investigating ways to prevent PROM. Taking antibiotics during the second and third trimester may reduce your risk. Taking vitamin C may also lower your chance of developing PROM. You can also take steps for a healthier pregnancy, like quitting smoking.