Prelabor rupture of membranes is the leaking of amniotic fluid from around the fetus at any time before labor starts.
After the membranes rupture, labor often soon follows.
If labor does not begin within 6 to 12 hours, the risk of infections in the woman and fetus increases.
If labor does not start soon after the membranes rupture and the pregnancy is 34 weeks or more and the fetus’s lungs are mature, labor is usually started artificially (induced).
If the pregnancy is less than 34 weeks and the fetus's lungs are not mature enough, the woman is usually hospitalized, monitored closely, and given corticosteroids to help the fetus's lungs mature and antibiotics to treat and prevent any infection that might trigger labor and/or harm the fetus.
If the pregnancy is less than 32 weeks, women may be given magnesium sulfate to reduce the risk of cerebral palsy.
Rupture of the membranes is commonly described as “the water breaks.” When the membranes break, the fluid within the membranes around the fetus (amniotic fluid) flows out from the vagina. The flow varies from a trickle to a gush. As soon as the membranes have ruptured, a woman should contact her doctor or midwife.
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Usually, the fluid-filled membranes containing the fetus rupture during labor. But occasionally in normal pregnancies, the membranes rupture before labor starts—prelabor rupture.
PROM may occur near the due date (at 37 weeks or later, when pregnancy is considered full term) or earlier (called preterm prelabor rupture if it occurs earlier than 37 weeks). If rupture is preterm, delivery is also likely to be too early (preterm).
Regardless of when prelabor rupture occurs, it increases the risk of problems such as
Intra-amniotic infection (infection of the membranes containing the fetus) and infections in the fetus
The fetus being in an abnormal position
Early detachment of the placenta (placental abruption)
Infection of the uterus can cause a fever, a heavy or foul-smelling vaginal discharge, or abdominal pain.
If prelabor rupture results in a preterm delivery, the premature newborn has an increased risk of the following:
Lung problems
Bleeding in the brain
Possibly death
When there is bleeding in the brain, the brain may not develop normally, causing problems such as cerebral palsy.
If the pregnancy is less than 24 weeks when the membranes rupture, the fetus's limbs may be deformed.
After the membranes rupture, contractions usually begin within 24 hours when the woman is at term but may not start for 4 days or longer if rupture occurs between 32 and 34 weeks of pregnancy.
Diagnosis of PROM
Examination of the vagina and cervix using a speculum
Using a speculum to spread the walls of the vagina, the doctor or midwife examines the vagina and cervix (the lower part of the uterus) to confirm that the membranes have ruptured and to estimate how much the cervix has opened (dilated).
If doctors see amniotic fluid leaking from the vagina, it is likely the membranes have ruptured. Doctors may do other tests (examine the fluid on a slide or check its pH).
If PROM is diagnosed and the fetus can survive outside the uterus, the woman is usually admitted to a hospital so that the status of the fetus can be determined.
Treatment of PROM
If the pregnancy is 34 weeks or more, usually artificial starting (induction) of labor
If the pregnancy is less than 34 weeks, usually rest, close monitoring usually in the hospital, antibiotics, and sometimes corticosteroids
If the pregnancy is less than 32 weeks, usually magnesium sulfate to prevent bleeding in the brain and problems with development of the newborn's brain
Doctors must balance the risk of infection in the uterus and in the fetus when delivery is delayed against the problems that may occur when a newborn is premature. Generally, a doctor or certified nurse midwife does the following:
If the pregnancy is 34 weeks or more, labor is induced because the fetus is assumed to be mature enough.
If the pregnancy is less than 34 weeks, the woman is closely monitored for signs of infection or labor in the hospital.
Sometimes doctors analyze a sample of amniotic fluid to check for signs of infection inside the amniotic sac. The sample is taken by amniocentesis, in which a doctor inserts a needle through the wall of the abdomen into the amniotic fluid and withdraws a sample from the membranes around the fetus. If infection is detected, doctors induce labor.
If the fetus is in severe distress or the uterus is infected, labor is usually induced and the baby is delivered regardless of the length of the pregnancy.
If labor needs to be delayed
If the pregnancy is less than 34 weeks, labor is delayed. The woman is advised to rest and to limit her activities as much as possible. She may be hospitalized so that she can be monitored closely. Her blood pressure, temperature, and pulse rate are usually recorded at least 3 times daily. An increase in temperature or pulse rate may be an early sign of infection. If an infection develops, labor is promptly induced and the baby is delivered.
If the membranes rupture between 23 and 34 weeks of pregnancy, corticosteroids are given to help the fetus’s lungs mature.
Doctors may also give women corticosteroids if the membranes rupture between 34 and 37 weeks of pregnancy if women are at risk of preterm delivery and have not been given any corticosteroids earlier in the pregnancy.
If the pregnancy is less than 32 weeks, women may be given magnesium sulfate intravenously. This medication appears to reduce the risk of bleeding in the newborn's brain and the resulting problems with development of the newborn's brain, such as cerebral palsy.
