In medical terms, PROM stands for premature rupture of membranes. It refers to a pregnant person’s amniotic sac (the “water”) breaking before labor contractions begin. When this happens at or after 37 weeks of pregnancy, it’s called term PROM. When it happens earlier than 37 weeks, it’s called PPROM, or preterm premature rupture of membranes. The distinction matters because the timing changes both the risks and how the situation is managed.
What Actually Happens During PROM
The amniotic sac is a tough, layered membrane that surrounds and protects the baby throughout pregnancy. It holds amniotic fluid, which cushions the baby, helps the lungs develop, and maintains a stable temperature. Normally, this membrane breaks during active labor or is broken by a healthcare provider during delivery. With PROM, the membrane ruptures on its own before labor starts.
The rupture can feel like a sudden gush of warm fluid or a slow, steady trickle that’s easy to confuse with urine or vaginal discharge. Some people aren’t sure their water has broken at all, which is why diagnostic testing is often needed.
Why the Membranes Break Early
Toward the end of pregnancy, the amniotic membrane naturally weakens. Enzymes that break down collagen become more active, and programmed cell death increases in the membrane tissue. Inflammatory signals accelerate this process, making the membrane progressively thinner and more fragile. In a normal pregnancy, this weakening is timed to coincide with labor. In PROM, it happens too soon.
Several factors increase the risk. Infections in the uterus or vagina are one of the most common triggers, because the inflammatory response they cause speeds up membrane breakdown. A history of PROM in a previous pregnancy raises the likelihood. Smoking, carrying multiples, having too much amniotic fluid, and certain cervical procedures can also contribute. In many cases, though, no clear cause is identified.
How PROM Is Diagnosed
Diagnosis typically starts with a sterile speculum exam. Your provider inserts a speculum to visualize the cervix and looks for pooling of amniotic fluid at the top of the vagina. If fluid is visibly collecting there, that alone can confirm the diagnosis.
When the picture isn’t clear, additional tests help. Nitrazine paper measures the pH of vaginal fluid: amniotic fluid is more alkaline than normal vaginal secretions, so the paper turns blue on contact. This test has high sensitivity (90 to 97%) but can give false positives from infections, urine, semen, or certain lubricants. Another classic test looks for a “ferning” pattern when dried vaginal fluid is viewed under a microscope, though its accuracy varies widely.
Newer biochemical tests have improved diagnostic precision. These detect specific proteins found only in amniotic fluid, with sensitivity rates above 96% and specificity above 91%. An ultrasound may also be used to check amniotic fluid levels around the baby, since unusually low fluid supports the diagnosis.
Term PROM vs. Preterm PROM
When membranes rupture at 37 weeks or later, the pregnancy is considered full term, and the baby is generally ready for life outside the womb. The main concern at this point is infection. The longer the interval between membrane rupture and delivery, the higher the risk of bacteria reaching the uterus. Among people whose water breaks at term before labor begins, about 70% will go into labor on their own within 12 hours. Roughly 90% will be in labor within 24 hours.
Preterm PROM, before 37 weeks, is more complex. The baby may not be mature enough for delivery, but continuing the pregnancy with ruptured membranes raises the risk of infection, placental separation, and umbilical cord complications. Management decisions depend heavily on exactly how far along the pregnancy is. Between 34 and 37 weeks, the balance tips more toward delivery. Earlier than that, the goal is often to buy time for fetal development while closely monitoring for signs of infection.
What Happens After Your Water Breaks
For term PROM, the two main options are inducing labor relatively soon or waiting to see if labor starts on its own (called expectant management). Both approaches are considered reasonable, but ACOG guidelines weigh the risks of infection against the benefits of allowing spontaneous labor. Most providers will discuss a timeline with you, since infection risk climbs with each passing hour after rupture.
For preterm PROM, the management is more involved. Depending on gestational age, you may receive medications to help the baby’s lungs mature faster and antibiotics to reduce infection risk. You’ll likely be monitored in the hospital with regular checks of your temperature, heart rate, and the baby’s status. The medical team is essentially balancing two competing clocks: fetal development and infection risk.
Risks and Complications
The primary risk after membrane rupture is chorioamnionitis, an infection of the amniotic fluid and membranes surrounding the baby. When PROM occurs very early in pregnancy (before the point of viability), the complication rate is significant. A 2025 ACOG practice advisory reported that maternal complications, including chorioamnionitis and hemorrhage, occurred in 43% of patients with very early membrane rupture who underwent expectant management. Rates of maternal sepsis were also higher in this group, at 4.6% compared to 1% in those who did not continue the pregnancy.
For the baby, risks depend on gestational age. At term, the main concern is infection. Earlier in pregnancy, prematurity itself is the biggest threat, bringing potential complications with breathing, feeding, and temperature regulation. Umbilical cord compression is another risk, since reduced amniotic fluid gives the cord less room to float freely.
PROM vs. Normal Water Breaking
It’s worth noting that your water breaking during active labor is not PROM. That’s normal, expected membrane rupture. PROM specifically describes rupture that happens before contractions begin. The word “premature” in the name refers to the timing relative to labor, not to the baby’s gestational age. This is a common source of confusion: term PROM means the baby is full-term, but the membrane rupture came prematurely in the sequence of labor events. Only when rupture occurs before 37 weeks does gestational prematurity also become a factor, and that’s when the condition is reclassified as PPROM.