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Intra-Amniotic Infection


by Antonette T. Dulay, MD

Intra-amniotic infection is infection of the tissues around the fetus, such as the fluid that surrounds the fetus (amniotic fluid), the placenta, the membranes around the fetus, or a combination.

  • Intra-amniotic infection increases the risk of problems in the woman and in the fetus.

  • Women usually have a fever and often have pelvic pain and a vaginal discharge.

  • Usually, doctors can diagnose the infection by doing a physical examination, but sometimes amniotic fluid must be analyzed.

  • Women are given antibiotics, and delivery is scheduled as soon as possible.

Intra-amniotic infection typically develops because bacteria from the vagina enter the uterus and infect the tissues around the fetus. Normally, mucus in the cervix, the membranes around the fetus, and the placenta prevent bacteria from causing infection. However, certain conditions can make it easier for bacteria to breach these defenses. These conditions include very early rupture of the membranes around the fetus (preterm premature rupture of the membranes—see Premature Rupture of the Membranes (PROM)) and, rarely, internal fetal monitoring and invasive procedures such as amniocentesis (see Procedures : Amniocentesis) or chorionic villus sampling (see Procedures : Chorionic Villus Sampling), which may be done to check for abnormalities before birth. The more time that passes between when the membranes rupture and delivery occurs, the more likely intra-amniotic infection is to develop, particularly if doctors or midwives do many pelvic examinations. Such examinations may introduce bacteria into the vagina and uterus.

Having bacteria that can cause infections in the genital tract also makes intra-amniotic infections more likely. These bacteria include group B streptococci and the bacteria that can cause sexually transmitted diseases or bacterial vaginosis. Women may not know that these bacteria are present, particularly if they have not had routine prenatal care, when tests for these bacteria would have been done.

Intra-amniotic infection is also more likely if labor starts early (preterm labor) or if the woman has not been pregnant before.

Intra-amniotic infection can increase the risk of the following problems in the fetus:

  • Preterm delivery or preterm premature rupture of membranes (intra-amniotic infection can cause as well as result from these problems)

  • Too little oxygen in the blood around the time of delivery

  • Infections, such as a bloodstream infection (sepsis), pneumonia, or meningitis

  • Seizures

  • Cerebral palsy

  • Death

Intra-amniotic infection can increase the risk of the following problems in the woman:

  • A bloodstream infection

  • Need for a cesarean delivery

  • Bleeding after delivery (postpartum hemorrhage)

  • A collection of pus (abscess) around the uterus

  • Infection of incisions made during delivery

  • Blood clots in the legs


Intra-amniotic infection usually causes fever and often causes abdominal pain and a discharge that can be foul-smelling. The heart rate of the fetus and the woman may be rapid. However, some women do not have any symptoms.


Doctors do a physical examination and can usually diagnose an intra-amniotic infection based on results of this examination. Sometimes they do a complete blood count, which may indicate that the number of white blood cells is abnormally large.

If preterm labor or premature preterm rupture of membranes occurs, doctors consider the possibility of infection even if women do not have typical symptoms. To confirm the diagnosis in such cases, doctors must remove a sample of the amniotic fluid and analyze it (amniocentesis).


If women have preterm premature rupture of membranes, doctors do pelvic examinations only if necessary. Doctors usually also give these women antibiotics intravenously or by mouth to reduce the risk of infection. Antibiotics can also delay delivery. Delaying delivery gives the fetus's lungs, which are still immature, time to mature.


Women with an intra-amniotic infection are given antibiotics intravenously. Delivery should not be delayed if

  • The delivery date is relatively close (that is, if the pregnancy has lasted about 36 weeks or more).

  • Preterm premature rupture of membranes occurs and the pregnancy has lasted at least 34 weeks.

For example, if labor has not started, labor may be artificially started (induced). Immediate cesarean delivery is not usually necessary.