The amniotic sac is an excellent barrier against all kinds of bugs, but occasionally one makes it past the defenses. When that happens, a bacterial infection such as chorioamnionitis can develop.

Here's everything expectant moms need to know about this infection, including the signs to look out for and treatment options.

What is chorioamnionitis?

Chorioamnionitis, also called intraamniotic infection, occurs in one to five percent of pregnancies. This bacterial infection can develop during pregnancy when bacteria enters:[1]

  • The amniotic membranes or fluid that surround and protect your baby
  • The placenta
  • The umbilical cord

What causes chorioamnionitis?

Most commonly, chorioamnionitis is caused by bacteria such as E. coli or by the group B streptococci (which you'll be tested for around week 35 of your pregnancy).

Women who experience premature rupture of the membrane are at increased risk for chorioamnionitis because bacteria can make it into the amniotic sac after it has ruptured, as are women who have longer duration labors.  

What are the symptoms of chorioamnionitis?

The symptoms of chorioamnionitis can include the following:

  • Fever
  • An increased heart rate in both you and your baby
  • A tender, painful uterus
  • Leaking, foul-smelling amniotic fluid

Your practitioner may be able to diagnose chorioamnionitis based on your symptoms, but if your membranes have not fully ruptured but your practitioner suspects chorioamnionitis, they may suggest an amniocentesis to remove amniotic fluid for testing.[2]

Infection of the amniotic membranes and fluid has been linked to preterm labor, and it also puts your baby at risk for an infection — so it's important to call your practitioner right away if you notice the symptoms above. 

Because chorioamnionitis risks go up with prolonged rupture of the membranes, seek treatment right away. Sometimes in term pregnancies, a mother's water may break but no contractions occur. While patients may wait for contractions to start, this can prolong labor and lead to increased risks of chorioamnionitis.

How is chorioamnionitis treated?

Chorioamnionitis can be serious, but treatment is available. If you are diagnosed with chorioamnionitis, you will likely be prescribed antibiotics to wipe out the bacteria. You and your baby will also be given antibiotics after delivery to make sure no further infections develop.

If the infection is more serious or if the baby's health is in danger, delivery — even if it's premature — may be the best treatment option available.[3]

What to do if you suspect chorioamnionitis

If you notice any leaking of amniotic fluid, no matter how small, be sure to call your practitioner so that they can determine if there is a real rupture. If you can't tell if you're leaking amniotic fluid, take the sniff test: Urine smells like ammonia; amniotic fluid has a sweeter smell, or if it's infected, it'll have a more foul smell. But always call your practitioner if there's any doubt.