Placental infections, also known as chorioamnionitis or intra-amniotic infection, are a serious condition during pregnancy. This inflammation of the fetal membranes and amniotic fluid due to bacterial infection has significant implications for both the pregnant individual and the developing baby. Understanding this condition helps pregnant individuals recognize signs and seek timely medical attention.
What is a Placental Infection?
A placental infection involves inflammation of the chorion and amnion, the two membranes surrounding the fetus, and the amniotic fluid. It is primarily caused by bacterial infection, leading to an inflammatory response within the uterus. It is estimated to affect approximately 1% to 5% of all births in the United States.
The most common pathway for infection to reach the placenta is through an ascending route from the vagina or cervix. Bacteria from the lower genital tract can travel upwards into the uterus, especially when the amniotic sac (bag of waters) has been ruptured for an extended period. Less common routes include hematogenous spread, where bacteria travel through the bloodstream to the placenta.
Several types of bacteria are commonly associated with placental infections. These can include Group B Streptococcus, Escherichia coli (E. coli), Gardnerella vaginalis, Mycoplasma hominis, and Ureaplasma urealyticum. When present in the amniotic fluid, these microorganisms can trigger the inflammatory process that characterizes chorioamnionitis.
Recognizing the Signs and Symptoms
Recognizing the signs and symptoms of a placental infection allows for prompt medical evaluation. The most common indicator is a maternal fever, often accompanied by other specific signs. Both the pregnant individual and the fetus may experience tachycardia (a rapid heart rate).
The uterus may also become tender or painful to the touch. Other signs include foul-smelling amniotic fluid or an unusual vaginal discharge. Some placental infections might be subclinical, presenting with subtle or less obvious signs, which makes early detection more challenging. Seek medical attention immediately if any of these signs are present.
Impact on Maternal and Fetal Health
Placental infections pose risks and complications for both the pregnant individual and the developing baby. For the mother, risks include postpartum hemorrhage (excessive bleeding after childbirth). The uterus may also experience uterine atony, where it fails to contract adequately after delivery, further contributing to bleeding.
The risk of endometritis (an infection of the uterine lining) also increases. Cesarean section delivery becomes more likely, carrying its own complications. In rare instances, a severe infection can lead to maternal sepsis, a life-threatening systemic response.
For the baby, placental infections increase the risk of preterm birth, which can lead to various health challenges. Newborns may develop neonatal sepsis (a bloodstream infection) or respiratory distress syndrome (a breathing disorder). In severe cases, especially in very premature infants, there is a potential for cerebral palsy and other long-term neurodevelopmental issues.
Diagnosis, Treatment, and Prevention
Diagnosis typically relies on a combination of clinical signs and symptoms. Healthcare providers primarily look for maternal fever combined with other indicators like maternal or fetal tachycardia, uterine tenderness, or foul-smelling amniotic fluid. While clinical diagnosis is often sufficient, laboratory tests may support the diagnosis.
Supportive tests can include an elevated maternal white blood cell count or, less commonly, a positive amniotic fluid culture obtained through amniocentesis. Once suspected, prompt administration of broad-spectrum intravenous antibiotics is the standard medical approach. Delivery of the baby, whether vaginal or via C-section, is often recommended upon diagnosis to resolve the infection, regardless of the gestational age.
Prevention strategies focus on good prenatal care, including prompt treatment of vaginal or urinary tract infections during pregnancy. Limiting the number of vaginal examinations once the membranes have ruptured can also help reduce the risk of ascending infections. If membranes rupture prematurely, antibiotics may be prescribed to prevent infection, especially if Group B Streptococcus is present.