Infections can be a serious concern during early pregnancy. While not the most common cause of miscarriage, certain infections can increase this risk. The majority of early miscarriages often stem from other factors, such as chromosomal abnormalities. Understanding the role infections can play provides important context for pregnant individuals.
What Constitutes Early Pregnancy Miscarriage?
Early pregnancy refers to the initial phase of gestation, encompassing the first 12 to 13 weeks. A miscarriage is the unexpected loss of a pregnancy before 20 weeks. Most miscarriages occur during this early pregnancy period, with about 80% happening within the first three months.
Miscarriages are common, affecting between 10% and 20% of all known pregnancies. This can include a “chemical pregnancy,” where a fertilized egg fails to implant properly, or a “missed miscarriage,” where the embryo has stopped developing but remains in the uterus without immediate symptoms.
Specific Infections Implicated in Miscarriage
Several types of infections, spanning bacterial, viral, and parasitic categories, have been linked to an increased risk of miscarriage. Bacterial vaginosis (BV), a common vaginal infection where the natural balance of bacteria is disrupted, has been associated with an increased risk of miscarriage. Urinary tract infections (UTIs) can also pose a risk if left untreated, as bacteria can potentially ascend to the uterus.
Foodborne bacterial infections are another concern. Listeria monocytogenes, found in contaminated foods like unpasteurized dairy or undercooked meats, can lead to listeriosis. Certain sexually transmitted infections (STIs) such as Chlamydia and Gonorrhea have also been associated with an increased risk of miscarriage.
Viral infections contribute to miscarriage risk. Rubella, or German measles, is dangerous if contracted in early pregnancy, with a high risk of miscarriage or stillbirth, especially in the first 8 to 10 weeks. Cytomegalovirus (CMV), a common herpes-type virus, can increase the risk of miscarriage if acquired during pregnancy. Parvovirus B19, which causes “fifth disease,” is most likely to cause miscarriage if the infection occurs during the first trimester.
Parasitic infections, such as toxoplasmosis, acquired from exposure to infected cat feces or undercooked meat, can also lead to pregnancy complications including miscarriage.
Mechanisms of Infection-Related Miscarriage
Infections can lead to miscarriage through several biological pathways, often involving the body’s immune response and direct damage to pregnancy tissues. One primary mechanism is inflammation, where a localized or systemic inflammatory response can negatively affect the uterine environment or the placenta. While some inflammation is normal for embryo implantation, an excessive or imbalanced inflammatory reaction can disrupt the receptive nature of the uterine lining, leading to miscarriage.
Certain pathogens can cause direct fetal or placental damage by crossing the placental barrier. For example, viruses like Rubella can directly interfere with fetal growth and development by inhibiting cell division and causing necrosis in chorionic villi. This direct harm can compromise placental function, which is essential for nutrient and gas exchange, leading to miscarriage.
Some infections may trigger uterine irritation and contractions, leading to miscarriage. While the exact pathways are still under investigation, changes in the vaginal microbiome, such as in bacterial vaginosis, can cause inflammation that might initiate contractions.
Maternal fever, often a symptom of infection, can also increase miscarriage risk. A sustained fever, especially temperatures above 103°F (39.4°C) in the first trimester, has been associated with this risk. While not every fever leads to miscarriage, the elevated body temperature can create an unfavorable environment for the developing embryo.
Recognizing Symptoms and Reducing Risk
Recognizing symptoms of infection during early pregnancy is important for medical intervention. Symptoms include fever, unusual vaginal discharge or odor, painful urination, or flu-like symptoms such as body aches and fatigue. While these symptoms do not always indicate a miscarriage, they warrant prompt medical attention to assess the cause and determine if treatment is needed.
Reducing the risk of infection during pregnancy involves several steps. Maintaining good hygiene is important, including frequent handwashing with soap and water, especially before eating and after using the restroom or handling raw foods. Safe food handling practices are also important. These include:
Thoroughly cooking meats.
Avoiding unpasteurized dairy products.
Washing fruits and vegetables well.
Avoiding cleaning cat litter boxes to prevent toxoplasmosis.
Practicing safe sexual behaviors.
Discussing vaccinations with a healthcare provider before or during pregnancy can protect against certain infections like Rubella. If concerning symptoms arise, such as vaginal bleeding, abdominal pain, or other signs of infection, it is important to contact a doctor or midwife immediately. Early diagnosis and appropriate treatment can help manage infections and reduce associated risks to the pregnancy.