Topic Overview

Before a baby is born, the amniotic sac breaks open, causing amniotic fluid to gush out or, less commonly, to slowly leak. When this happens before contractions start, it is called prelabour rupture of membranes (PROM). PROM can occur at any time during pregnancy.

When PROM occurs before 37 completed weeks of pregnancy, it usually leads to preterm labour. You may hear this early PROM referred to as preterm prelabour rupture of membranes, or pPROM.

PROM is often unexpected, and the cause is often hard to identify. Known causes of PROM include:

• Uterine infection, which is a common trigger of pPROM.
• Overstretching (distension) of the uterus and amniotic sac. Multiple fetuses or too much amniotic fluid (polyhydramnios) are common causes of distension.
• Trauma, as from an injury.

Course of pPROM

Preterm labour usually begins shortly after pPROM occurs. Sometimes, when a slow leak is present and infection has not developed, contractions may not start for a few days or longer. In general, the later in a pregnancy PROM occurs, the sooner the onset of labour.

Sometimes a leak high up in the amniotic sac may reseal itself so that preterm labour does not start or subsides.

In rare cases, a pregnancy can be carried to term if pPROM occurs in the second trimester.

Standard treatment for pPROM

Standard treatment for pPROM includes antenatal corticosteroid medicines, which are used to speed up fetal lung maturity at or before 34 weeks of pregnancy.

Other treatment for pPROM

Other treatment for pPROM may include:

• An observation period or expectant management.
• Antibiotics, given to treat or prevent amniotic fluid infection.
• Starting (inducing) labour with medicine if labour does not start naturally. This is meant to speed up delivery and reduce the risk of infection. Labour can be induced if there is strong evidence that the fetus's lungs are mature enough, or if you have an infection.

Controversial treatment for pPROM

After amniotic membranes have ruptured, tocolytic medicine is less effective in slowing or stopping preterm labour contractions. But tocolytic medicine is sometimes used to delay a preterm birth long enough for antibiotics and antenatal corticosteroid medicine to work (24 hours) or long enough to transport the mother to a hospital that has a neonatal intensive care unit (NICU).^{footnote 1}