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Chorioamnionitis is an infection of two membranes of the placenta (the chorion and the amnion) and the amniotic fluid that surrounds the baby. Chorioamnionitis can cause bacteremia (blood infection) in the mother and may lead to preterm birth and serious infection in the newborn baby. Other terms for chorioamnionitis include intra-amniotic infection and amnionitis.


The infection, which occurs in about 2 percent of all pregnancies, is caused by bacteria that reach the uterus through the vagina.

In rare cases, chorioamnionitis occurs when there is no obvious rupture of the membranes.
The infection may be the cause of some cases of preterm labor.
For this reason, doctors check first for infection in women who have preterm labor.
The infection occasionally occurs early in pregnancy in women who have a type of bacteria called beta streptococcus in their vagina.
Because this bacteria can cause severe infections, such as pneumonia, in the newborn, a doctor tests a woman's vaginal secretions to determine if beta streptococcus is present.
If it is, the infection is treated immediately.


Symptoms of chorioamnionitis include fever and tenderness in the uterus. The baby may show signs of infection, such as a fever or a higher-than-normal heart rate.

Symptoms may include:

The symptoms of chorioamnionitis may resemble other conditions or medical problems. Always consult your physician for a diagnosis.

Risk of neonatal infection increases as the duration of ruptured membranes lengthens. Chorioamnionitis may initiate uteroplacental bleeding or a placental abruption. Labor and delivery may be rapid in the presence of chorioamnionitis. Alternatively, infection may cause uterine atony, requiring labor to be augmented with Pitocin. Ultimately, a poor labor pattern may require an instrumented delivery or a cesarean delivery. Each of these antepartum and intrapartum factors must be considered when evaluating the newborn for the presence of bacterial infection.


In addition to a complete medical history and physical examination, chorioamnionitis is diagnosed by symptoms and by laboratory tests for infection. Testing of the amniotic fluid by amniocentesis may be needed.

White blood cell (WBC) counts or C-reactive protein (CRP) levels in maternal blood is commonly used to predict acute chorioamnionitis when maternal fever is present. Different studies have supported or refuted the use of CRP to diagnose chorioamnionitis. The CRP may be better than peripheral WBC counts in predicting the risk of chorioamnionitis, especially if the mother has received corticosteroids. Corticosteroids may falsely increase the total WBC count.

Other investigators have suggested that the alpha1-proteinase inhibitor complex in maternal blood is better than either CRP or WBC count to predict amniotic fluid infection.

Ultrasonography may be used to ascertain fetal well-being. A biophysical profile may provide information about the status of the fetus. Low biophysical profile scores may be an indirect indicator of bacterial infection in the fetus. Imaging has no direct means of indicating fetal infection with bacteria.


Specific treatment for chorioamnionitis will be determined by your physician based on:

  • Your overall health and medical history

  • Extent of the condition

  • Your tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the condition

  • Your opinion or preference

The infection is treated with antibiotics, usually given intravenously in the hospital. Because antibiotics given to woman do not reach the baby in quantities sufficient to treat its infection, immediate delivery is recommended. If the baby is born with severe infection, he or she is given antibiotics intravenously to prevent or treat other infections - such as pneumonia or meningitis - that can be caused by the same bacteria.


Seriously or critically ill newborns with early-onset bacterial infections require parenteral fluids and nutrition until their condition improves. Infections involving the GI tract may need a special approach to feeding when feedings are reinstituted


For the mother with chorioamnionitis, serious infectious complications include endometritis, localized pelvic infections requiring drainage, and intra-abdominal infections. Maternal chorioamnionitis or other secondary infectious complications may cause thrombosis of pelvic vessels and the potential for pulmonary emboli.

Serious complications, including septic shock, pulmonary hypertension, respiratory failure, and meningitis, do occur in early-onset bacterial infections of the neonate. The duration of hospitalization can be quite prolonged in an extremely premature infant because of infectious complications such as maternal chorioamnionitis or congenital pneumonia. Either condition increases the probability of chronic lung disease in prematurely born and term babies.

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