Chronic villitis is an inflammatory condition affecting the placenta, the temporary organ that develops during pregnancy to provide oxygen and nutrients to the growing baby. It involves inflammation of the placental villi, which are essential for the exchange of substances between mother and fetus. This condition is diagnosed through a microscopic examination of the placenta after birth. Its presence can influence pregnancy outcomes.
Understanding Chronic Villitis
The placenta contains numerous tiny, finger-like projections called villi. These villi increase the surface area for the exchange of oxygen, nutrients, and waste products between the mother’s bloodstream and the developing fetus. Chronic villitis occurs when these villi become inflamed, impairing their efficient function and reducing the placenta’s effectiveness in transferring essential resources to the baby.
The term “chronic” in chronic villitis indicates that the inflammation develops gradually over time. This distinguishes it from acute forms of villitis, which might arise from specific infections and involve different types of inflammatory cells. Chronic villitis involves specific immune cells, primarily maternal lymphocytes, infiltrating the fetal tissue of the chorionic villi.
Factors Contributing to Chronic Villitis
The exact causes of chronic villitis are not fully understood, leading many cases to be classified as “villitis of unknown etiology” (VUE). One leading theory suggests it involves a maternal immune response, similar to a rejection reaction seen in organ transplants, where the mother’s immune system identifies the fetal tissue in the placenta as foreign. Maternal immune cells, particularly CD8+ T lymphocytes, infiltrate the placental villi.
Though less common than for acute forms, some infections have been linked to its development. Certain viral infections, including some human herpesviruses, have been detected more frequently in placentas with chronic villitis. However, no specific infectious agent is identified, supporting the theory of an immune-mediated origin. Demographic factors like maternal body mass index and multigravidity have also been reported as associations.
How Chronic Villitis Affects Pregnancy
Chronic villitis can impact pregnancy by disrupting the placenta’s ability to support fetal development. The inflammation within the villi reduces the efficiency of nutrient and oxygen transfer from the mother to the baby. This impaired function can lead to several adverse outcomes, with severity depending on the extent and grade of the villitis.
One common complication is fetal growth restriction (FGR), where the baby does not grow as expected. Placentas affected by chronic villitis are smaller than average for gestational age. In severe cases, particularly with high-grade villitis, FGR is a frequent finding, occurring in a significant percentage of affected pregnancies.
The condition can also increase the risk of preterm birth. Additionally, chronic villitis has been associated with oligohydramnios, a condition characterized by low levels of amniotic fluid. Chronic villitis may contribute to fetal distress or stillbirth, although outcomes vary widely among affected pregnancies.
Identifying and Managing Chronic Villitis
Chronic villitis is commonly diagnosed after birth, through a microscopic examination of the placenta by a pathologist. This post-delivery assessment is important for identifying the characteristic inflammatory cells within the chorionic villi. While direct diagnosis during pregnancy is not possible, healthcare providers may suspect placental issues based on monitoring fetal growth and well-being.
During pregnancy, if chronic villitis is suspected due to concerning signs like slowed fetal growth, monitoring strategies may include regular ultrasound examinations. These scans help assess fetal growth patterns and amniotic fluid levels. Doppler studies, which measure blood flow in fetal vessels, can also provide information about placental function.
There is no specific treatment to eliminate chronic villitis itself. Management focuses on closely monitoring the pregnancy and mitigating its potential effects. This supportive care might involve surveillance of fetal development to ensure timely interventions if complications arise. Some studies have explored the use of low-dose aspirin or corticosteroids in subsequent pregnancies with a history of chronic villitis, though more research is needed to confirm their effectiveness.
Outlook for Future Pregnancies
For individuals who have experienced chronic villitis in a previous pregnancy, recurrence is possible in future pregnancies. Studies indicate that chronic villitis can recur in a significant percentage of subsequent pregnancies, with estimates ranging from 27% to 54%. The risk of recurrence can be more than double compared to those without the condition.
In cases of recurrent chronic villitis, the extent of chronic inflammation and other placental issues, such as fetal vascular malperfusion, may be more pronounced in the later pregnancy. Due to this risk, closer monitoring is recommended for subsequent pregnancies. This might include more frequent ultrasound scans to track fetal growth and placental health.
While chronic villitis is associated with adverse outcomes, many pregnancies affected by the condition result in live births. The prognosis for babies affected by chronic villitis varies widely depending on the severity of the placental involvement and the resulting impact on fetal development. Early detection and management can help improve outcomes.