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Infections Medical emergency

Chorioamnionitis

Also known as Intra-amniotic infection, Intraamniotic infection, Triple I, Amnionitis. Most often during labor or after your water breaks, and more common with preterm birth.

Chorioamnionitis is an infection of the membranes and fluid that surround your baby, and it needs treatment right away. Most often it happens when bacteria that normally live in the vagina travel up into the uterus after your water has broken, so it is closely tied to labor and to a bag of waters that has been open for a while. The usual first clue is a fever during labor, sometimes with a tender belly, a fast heartbeat in you or your baby, or fluid that smells off. Treated promptly with antibiotics through a vein and a timely delivery, most parents and babies do well. Left untreated it can turn serious for both of you, which is why a fever and belly pain in pregnancy are never brushed off.

Know the warning signs When to call a provider
How common
2% to 5% of births
About 4% at term, and far higher with preterm birth or a long time after the water breaks.
When
Usually in labor
Most often once your water has broken, and more common in preterm births.
Urgency
Emergency
A fever in labor or with your water broken is treated urgently.
Outlook
Good with prompt care
IV antibiotics and a timely delivery resolve the large majority of cases.

This can be a medical emergency. A temperature of 100.4 F (38 C) or higher during pregnancy or labor, especially once your water has broken If this happens, go to the ER or call 911 right away.

Understanding it

What is chorioamnionitis?

Chorioamnionitis is an infection, or inflammation, of the chorion and amnion, the two membranes that form the bag of waters, along with the amniotic fluid inside and sometimes the placenta. Because the fluid can be inflamed whether or not bacteria are actually grown from it, doctors increasingly use the umbrella term Triple I, meaning intrauterine infection or inflammation or both. It complicates roughly 2% to 5% of births in the United States, about 4% at term, and becomes far more common with preterm birth or when the water has been broken for a long time.

In most cases it is an ascending infection. Bacteria that normally live in the vagina and lower digestive tract move upward into the uterus, most easily once the membranes have ruptured and that barrier is open. The usual culprits are ordinary residents like group B strep, E. coli, anaerobes, and genital mycoplasmas such as Ureaplasma, not organisms you caught from anyone.

The reason it is treated as an emergency is the risk to your baby and to you. A baby can develop an infection of the blood, lungs, or the lining around the brain in the first days of life, and the infection can also trigger early labor. For you, it raises the odds of a uterine infection after birth, heavier bleeding, and, less often, a serious bloodstream infection.

The good news is that treatment is well established and works. Antibiotics through a vein, started promptly, together with delivering your baby, clear the infection in the large majority of cases. Chorioamnionitis by itself is not a reason for an immediate cesarean, so many parents still have a vaginal birth.

Symptoms

What are the symptoms?

Unlike some pregnancy infections, chorioamnionitis usually makes itself known. A fever during labor, or after your water breaks, is the most common and important sign. The other clues can be subtle, so the diagnosis rests on the whole picture rather than any single symptom.

Early signs

  • A fever, the most common and important sign
  • A tender or painful uterus or lower belly
  • A faster than usual heart rate in you
  • A fast fetal heart rate, often the first thing noticed on the monitor
  • Amniotic fluid or vaginal discharge that smells foul or looks cloudy or discolored
  • Chills, sweating, or simply feeling unwell

Emergency signs — call 911

  • A temperature of 100.4 F (38 C) or higher during pregnancy or labor, especially once your water has broken
  • Fever together with belly or uterine pain, chills, or foul-smelling fluid
  • Your water has broken and you feel feverish, shaky, or unwell, even a little
  • A racing heartbeat, dizziness, fainting, or confusion, which can mean the infection is spreading
  • Your baby is moving less than usual, or you simply feel something is wrong, get checked now

Why it matters

Risks to you and baby

Infection in your newborn

The biggest concern is that your baby is exposed to the same bacteria. In the first days of life this can cause a bloodstream infection (sepsis), pneumonia, or meningitis. Prompt antibiotics for you, close newborn monitoring, and treatment when needed make this far less likely.

Preterm birth

Chorioamnionitis is a common cause of early labor and delivery, and infection and prematurity together add to a baby's risks. When it develops preterm, your team weighs the danger of the infection against the benefit of more time in the womb.

Endometritis, a uterine infection after birth

The lining of the uterus can stay infected after delivery, causing fever, belly pain, and foul-smelling discharge. It is more common after a cesarean, happening in up to about a third of those cases, and it is treated with antibiotics.

Heavier bleeding after birth

An inflamed uterus does not always contract firmly after delivery, and a uterus that stays soft can bleed more than usual (postpartum hemorrhage). Your team watches for this and has medications and other measures ready.

Serious infection in you

Less often, the bacteria reach your bloodstream (bacteremia or sepsis), or a cesarean wound becomes infected, and pelvic blood clots are an uncommon risk. Prompt IV antibiotics are aimed squarely at preventing these.

How it's found

How is it diagnosed?

Chorioamnionitis is usually a clinical diagnosis, made at the bedside from a fever plus other signs rather than from one test. Labs support the picture, and sampling the fluid directly is rarely needed.

Your temperature and vital signs

A single fever of 102.2 F (39 C), or 100.4 F (38 C) or higher along with another sign, is the entry point. A fast heart rate in you is also noted.

Fetal heart monitoring

A persistently fast fetal heart rate, above about 160 beats per minute, is one of the supporting signs and a reason to look closer.

Exam of your belly and the fluid

A tender uterus, and amniotic fluid or discharge that smells foul or looks purulent, point toward infection.

Blood tests

A high white blood cell count, above about 15,000, supports the diagnosis, though it can also rise in normal labor, so it is read alongside the other findings.

It is usually diagnosed right in labor or after the water breaks, when a fever appears. It is only occasionally confirmed by testing the fluid directly with amniocentesis, which is reserved for unclear situations such as preterm labor that will not settle.

Treatment

How is it managed?

Two things go together and neither waits: antibiotics through a vein to treat the infection, and delivering your baby so the source of the infection is removed.

Treatment paths

As soon as chorioamnionitis is suspected, you are started on broad-spectrum antibiotics through a vein and given medicine such as acetaminophen to bring down fever. Your baby is monitored continuously, and a plan is made to deliver in a timely way. The infection itself is not a reason to rush to a cesarean, so if labor is progressing safely a vaginal birth is still expected.

Medication

The standard combination is ampicillin plus gentamicin through a vein. If you have a cesarean, a dose of clindamycin or metronidazole is usually added to cover anaerobic bacteria. For a penicillin allergy, cefazolin, clindamycin, or vancomycin is used instead, and acetaminophen treats the fever.

Monitoring

Your baby's heart rate is watched closely during labor, and after birth your newborn is checked, and sometimes treated, for infection. You are watched for a day or more afterward for ongoing fever, a tender uterus, heavy bleeding, or other signs of endometritis, and antibiotics are often continued for a time after delivery, especially after a cesarean.

Can it recur?

It can, though most future pregnancies are unaffected. In one large study about 6% of people who had chorioamnionitis in a first birth had it again in the next, compared with about 2% who had not, roughly double the risk. Much of that is tied to a tendency toward ruptured membranes and preterm labor, so care in a future pregnancy focuses on those, including group B strep screening and prompt attention when your water breaks.

What you can do

Can it be prevented?

  • Get group B strep screening and labor antibiotics

    A vaginal and rectal swab at 36 to 37 weeks shows whether you carry group B strep, and antibiotics during labor if you do lower the chance of a GBS-driven infection reaching your baby.

  • Get seen promptly when your water breaks

    Once the membranes rupture, the barrier against bacteria is open, so let your team know right away and follow their timeline for delivery. Keeping vaginal exams to what is needed also helps.

  • Treat infections during pregnancy and keep prenatal visits

    Having urinary infections, bacterial vaginosis, and sexually transmitted infections checked and treated, and going to your prenatal appointments, lowers the risk. Chorioamnionitis cannot always be prevented, but these steps reduce it.

Who is more at risk

Risk factors

A long time with your water broken
The single clearest risk factor. The longer the membranes are open before birth, the more chance bacteria have to move up into the uterus.
Membranes broken more than 24 hours before delivery is a leading risk factor
Preterm labor or preterm rupture of membranes
Infection and inflammation are closely linked with going into labor or breaking your water early, and the risk of intra-amniotic infection is much higher in preterm births.
A long labor and many vaginal exams
Prolonged labor and repeated vaginal exams after the water breaks both give bacteria more opportunity to reach the uterus.
Group B strep or other genital infections
Carrying group B strep, or having bacterial vaginosis or certain sexually transmitted infections, raises the risk, which is one reason these are screened for and treated.
A first pregnancy and other factors
A first birth, meconium-stained fluid, internal fetal monitoring during labor, and smoking or alcohol use are also associated with a higher risk.

Do not wait

When to call your provider or 911

  • Call 911 or go to the ER for a high fever with confusion, trouble breathing, fainting, or a pounding heartbeat, which can mean an infection is spreading.
  • Be seen right away for a temperature of 100.4 F (38 C) or higher in pregnancy, especially with belly pain, chills, or after your water has broken.
  • Call the moment your water breaks, and go in as your team advises, so infection can be caught early and antibiotics started on time.
  • Report foul-smelling fluid or discharge, a tender belly, or your baby moving less, and do not wait to see if it passes.
  • After birth, call for fever, worsening belly pain, heavy bleeding, or foul-smelling discharge, which can signal a uterine infection.

Talking to your team

Questions to ask your provider

  • Do I have chorioamnionitis, or are you watching me closely for it?
  • Which antibiotics am I getting, and will they continue after my baby is born?
  • Does this mean I need a cesarean, or can I still aim for a vaginal birth?
  • How will you monitor my baby during labor and after delivery?
  • Will my baby need antibiotics, blood tests, or time in the NICU?
  • My water has been broken for a while, what is the plan and timeline for delivery?
  • Does having this raise my risk in a future pregnancy, and what can lower it?

Keep reading

More on chorioamnionitis

All pregnancy guides articles

Good to Know

Chorioamnionitis FAQs

Common questions about chorioamnionitis, answered.

Is chorioamnionitis an emergency?

It is treated as one, because an untreated infection can harm you and your baby. The reassuring part is that the treatment, antibiotics through a vein and a timely delivery, works well, and with prompt care most parents and babies do fine.

Does chorioamnionitis mean I need a C-section?

Usually not. The infection by itself is rarely a reason for an immediate cesarean. If your labor is progressing safely, a vaginal birth is still expected, and a cesarean is done only for the usual obstetric reasons.

Will my baby be okay?

Most babies do well when the infection is treated promptly. Because your baby can be exposed to the same bacteria, the newborn team watches closely for signs of infection and treats early if needed, which is why delivery happens somewhere ready to care for your baby.

Did I do something to cause this?

No. Chorioamnionitis comes from ordinary bacteria that live in the vagina and gut moving up into the uterus, usually after the water breaks. It is not caused by poor hygiene and it is not a sexually transmitted infection.

Why do I need both antibiotics and delivery?

Antibiotics treat the infection and reduce what reaches your baby, and delivering removes the infected fluid and membranes that keep feeding it. Used together they clear the infection far better than either one alone.

Can chorioamnionitis be prevented?

Not always, but the risk can be lowered. Group B strep screening with antibiotics in labor, prompt care once your water breaks, limiting vaginal exams, and treating vaginal and urinary infections during pregnancy all help.

Will I get it again in my next pregnancy?

Probably not, but the risk is somewhat higher. In one large study about 6% of people who had it in a first birth had it again next time, versus about 2% who had not. Much of that traces back to a tendency toward early or prolonged rupture of the membranes, so that is where prevention focuses.

What does Triple I mean?

It stands for intrauterine infection or inflammation or both. Doctors adopted the term because the fluid around your baby can be inflamed whether or not bacteria are actually found, so it describes the condition more accurately than the older word chorioamnionitis.

Medically Reviewed · Updated

Reviewed by Dr. Grace Lin, MD, FACOG · OB-GYN

Obstetrician-gynecologist focused on reproductive and sexual health for women: pregnancy, BV, yeast, trichomoniasis and HPV/cervical screening. Our editorial guidelines →

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