If you're pregnant, you might want to know about when your water will break, how it will feel and what to do after it happens. Knowing what to expect when your water breaks can help you get ready for your baby's birth.

During pregnancy, a fluid-filled sac called the amniotic sac surrounds the baby. Most often, at the start of labor or during labor the thin tissue around the sac, called the membrane, breaks. This is known as water breaking on its own.

If your water breaks before labor starts, it's called prelabor rupture of membranes (PROM). It once was called premature rupture of membranes.

When your water breaks, you might feel wetness in your vagina or on the thin layor of skin between your genitals and your anus, called the perineum. Small amounts of watery fluid may come from your vagina a little at a time or in a steady flow. Or clear fluid or pale yellow fluid might pour out.

It's not always easy to know if your water has broken. It might be hard to tell if the liquid is amniotic fluid or urine. Feeling only wetness or having a trickle of fluid can make it harder to tell.

If you're not sure whether your water has broken, contact your healthcare professional right away. Or go to your hospital or birthing center right away. A member of your healthcare team can check to see if you're leaking amniotic fluid.

Your healthcare team might do an ultrasound to check the amount of amniotic fluid around the baby. You may have an exam of the vagina, and your care team may take a sample of fluid from the vagina to test for prelabor rupture of membranes. The team also checks you and your baby to decide what to do next.

Most often, if the water breaks and the pregnancy is full term, labor soon follows. It may have begun already.

But labor doesn't always start after the water breaks. If you have prelabor rupture of membranes, your healthcare team might help your uterus contract before labor begins on its own. This is called labor induction. The longer it takes for labor to start after your water breaks, the greater the risk of you or your baby getting an infection.

If your water breaks before the 37th week of pregnancy, it's known as preterm prelabor rupture of membranes. This is sometimes called preterm PROM. Your water breaking too early might have no known cause. But the following can increase the risk:

• Having had preterm prelabor rupture of membranes in an earlier pregnancy.
• Swelling and irritation, called inflammation, of the fetal membranes. This is called intra-amniotic infection.
• Vaginal bleeding during the second and third trimesters.
• Smoking or using illicit drugs during pregnancy.
• Being underweight with poor nutrition.
• A shortened cervix. The cervix is the lower end of the uterus that connects to the vagina.

Health issues that can be caused by preterm prelabor rupture of membranes include:

• Infection for you or the baby.
• The placenta peeling away from the inner wall of the uterus before delivery. This is called placental abruption.
• Problems with the umbilical cord.

Premature birth also puts the baby at risk of other health concerns.

If you have preterm prelabor rupture of membranes and you're at least 34 weeks pregnant, your healthcare team might suggest delivery to keep you or the baby from getting an infection. If there are no signs of infection or other concerns about the baby, though, research suggests that pregnancy can go on safely for a time. But it's likely that your healthcare team will need to watch you and the baby closely in the hospital. This is called watchful waiting.

If you're between 24 and 34 weeks pregnant, your healthcare team likely will try to delay delivery until your baby has more time to grow. Antibiotics can help prevent an infection and shots of steroid can speed your baby's lung growth. If you're less than 32 weeks pregnant and at risk of delivering within a few days, you might get magnesium sulfate to protect the baby's nervous system.

Starting at week 23 of pregnancy, your healthcare team might suggest steroids if you're at risk of delivering within seven days. This also is true if you're between weeks 34 and 36 and six days of pregnancy, at risk of delivering within seven days, and you haven't had steroids already. You might get steroids again if you're less than 34 weeks pregnant, at risk of delivering within seven days and you had the first steroids more than 14 days before.

If you're less than 24 weeks pregnant, your healthcare team talks with you about the risks of having a baby that early and the risks of trying to delay labor.

During active labor, if your cervix has opened and thinned, and the baby's head is deep in your pelvis, your healthcare professional might use a plastic hook to make a small hole in the amniotic sac. This is called amniotomy. It causes the water to break and may start contractions or make them stronger.