Chorioamnionitis is a bacterial infection that occurs when microorganisms ascend from the lower genital tract into the uterus. This infection targets the amniotic fluid and the membranes—the chorion and amnion—that surround the fetus during pregnancy. The condition is a serious concern because it can lead to complications for both the birthing parent and the baby, including increasing the risk of preterm birth. Prompt identification of risk factors and swift medical management are important for reducing the potential harm associated with this intrauterine infection.
Identifying Key Risk Factors
A person’s vulnerability to chorioamnionitis increases with certain obstetric events and pre-existing conditions. One significant factor is the premature or prolonged rupture of membranes (PROM), where the amniotic sac breaks before labor or remains broken for an extended duration. This rupture removes the physical barrier protecting the uterine environment, allowing bacteria from the vagina to ascend into the amniotic space. The risk of infection rises proportionally with the length of time that passes after the membranes rupture.
Preterm labor is closely associated with chorioamnionitis, with the infection found in a higher percentage of preterm deliveries compared to full-term births. The underlying inflammation from a subclinical infection can sometimes trigger the labor process itself. Existing lower genital tract infections, such as Group B Streptococcus (GBS), bacterial vaginosis, or certain sexually transmitted infections (STIs), introduce a higher concentration of potential pathogens near the cervix. Screening and treating these conditions before or during pregnancy is a direct way to reduce the microbial load that could cause chorioamnionitis.
The duration of labor further influences risk, as prolonged labor provides more opportunity for bacteria to colonize and spread upward. The number of digital vaginal examinations performed after the membranes have ruptured also directly correlates with the likelihood of infection. Each internal examination can potentially push bacteria higher into the uterus, which is why medical providers carefully limit these checks once the water has broken. Other individual factors, like having a first pregnancy, a short cervix, or the use of internal fetal monitoring devices, can also increase the overall risk profile.
Actionable Strategies for Prevention
Proactive screening and treatment for common infections represent a primary strategy in preventing chorioamnionitis. All pregnant individuals are screened for Group B Streptococcus (GBS) colonization, typically via a combined vaginal and rectal swab between 35 and 37 weeks of gestation. If the GBS test is positive, or if a person has risk factors like a previous baby with GBS disease, intravenous antibiotic prophylaxis is administered during labor. This treatment significantly reduces the risk of the baby acquiring the infection during birth, decreasing the chances of GBS-related chorioamnionitis.
Routine prenatal care also includes screening for and managing other infections that could contribute to the risk, such as urinary tract infections (UTIs) and STIs. Treating asymptomatic bacteriuria is important because even an undetected UTI can introduce pathogens that may eventually ascend. Beyond specific screenings, general hygiene advice focuses on maintaining the health of the lower genital tract, which includes avoiding douching, which can disrupt the natural protective balance of vaginal flora. Addressing any symptoms of unusual discharge or irritation promptly with a healthcare provider ensures that minor infections are treated before they become a larger problem.
Specific medical management during labor changes once the membranes have ruptured, as this is when the infection pathway opens up. Healthcare providers strive to minimize the number of digital vaginal examinations performed, especially in cases of prolonged rupture of membranes. This practice is based on evidence that limiting internal checks reduces the frequency of introducing bacteria into the sterile uterine cavity. When premature rupture of membranes (PPROM) occurs before 37 weeks, a course of prophylactic, or preventative, antibiotics is often initiated to prolong the pregnancy and reduce the risk of chorioamnionitis.
The use of antibiotics in PPROM cases buys time for fetal lung development while controlling the threat of uterine infection. In all cases where the membranes have ruptured, the patient and provider collaboratively determine the optimal timing for delivery to balance the risks of prematurity against the rising danger of infection. The goal is to safely deliver the baby before the ascending bacteria can establish a full-blown infection.
Recognizing Symptoms and Medical Intervention
Recognizing the signs that an infection may be underway is important for a rapid response, as chorioamnionitis is considered a medical urgency. The most consistent clinical finding is a maternal fever, typically defined as a single temperature reading of 102.2°F (39.0°C) or a persistent temperature of 100.4°F (38.0°C) or higher. Fever is often accompanied by other symptoms, including a rapid maternal heart rate, known as maternal tachycardia, which is a rate exceeding 100 beats per minute.
The fetus may also show signs of distress, most commonly demonstrated by fetal tachycardia, a sustained heart rate above 160 beats per minute. Clinical diagnosis is typically made when a maternal fever is present along with at least one other sign, such as uterine tenderness upon physical examination or the presence of foul-smelling or purulent amniotic fluid. Any suspicion of chorioamnionitis requires immediate medical consultation and intervention to prevent serious complications for both the mother and the newborn.
Once the diagnosis is suspected or confirmed, the standard treatment protocol involves the prompt administration of broad-spectrum intravenous (IV) antibiotics. Common regimens often include medications like ampicillin and gentamicin, which target the bacteria most likely to be involved in the infection. While the infection is being treated, the healthcare team often determines that expedited delivery is necessary to minimize the baby’s exposure to the infected environment. Delivering the baby and placenta removes the source of the infection, which is the most effective step in managing chorioamnionitis.