Bacterial and Viral Infections Linked to Miscarriage

Some viral and bacterial infections can increase your risk of pregnancy loss. While a few infectious illnesses are well-documented risk factors for miscarriage, other studies suggest some common vaginal infections can increase your risk of miscarriage. If you are concerned you may have any of these infections, talk to your doctor about getting testing and treated.

Bacterial Vaginosis

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Bacterial vaginosis (BV) is a common vaginal infection that causes a fish-like odor; itching; burning after intercourse; and thin, white or gray vaginal discharge. ​

While BV can produce symptoms, some women with BV have no symptoms at all. Some studies have tied bacterial vaginosis to both first- and second-trimester miscarriage, as well as higher risk of preterm delivery. However, researchers are still examining how BV relates to miscarriage.

Your gynecologist can test you for BV during your pelvic exam by taking a swab and testing it for the presence of bacteria. If you have BV, a vaginal cream-based antibiotic can help clear up any infection you may have.


Having chlamydia and other sexually transmitted diseases can increase your odds of developing pelvic inflammatory disease (PID), an inflammatory condition which is a known risk factor for ectopic pregnancy. Signs of PID may include pelvic pain, discomfort, and fevers. 

Researchers have found evidence that chlamydia might increase miscarriage as the bacteria can alter your immune response against an early pregnancy. Symptoms of chlamydia can include discharge, itching, vaginal pain, rectal pain, and discharge and pain during sex and urination. Many women with chlamydia won't experience any symptoms.

If you have chlamydia or PID, you will need to be treated with antibiotics. PID requires a slightly longer antibiotic treatment than chlamydia does. Your doctor can diagnose chlamydia by testing a swab taken from a pelvic exam or with a blood test. If you have chlamydia which was untreated for a long period of time and your doctor suspects PID, they may do an ultrasound to look for signs of chronic or more severe inflammation. 

Foodborne Infections

Certain types of bacterial food poisoning, such as Listeria and Salmonella infections, are tied to miscarriage risks. Listeria is a type of bacteria most commonly found in unpasteurized cheese and deli meats ​and can cause the disease listeriosis. Salmonella is common in poultry, red meat, and uncooked eggs.


Some cats carry a bacteria called Toxoplasma gondii, which can be found in cat feces, and is why pregnant women should not change the litter box. These bacteria cause a disease called toxoplasmosis, which can cause miscarriage or congenital problems in a baby.

Parvovirus B19 (Fifth Disease)

Parvovirus B19 causes a relatively mild illness called fifth disease. The condition is usually mild in children and otherwise healthy adults. Most people catch the disease at some point during childhood, leading to permanent immunity. Parvovirus B19 can cause hydrops fetalis, a serious condition leading to fluid buildup in the fetus, if a non-immune pregnant woman is exposed.

According to the CDC, less than 5% of women who get parvovirus B19 during pregnancy end up miscarrying.


Rubella, also called German measles, can cause congenital birth defects if you catch it while pregnant during your first trimester. Rubella can also cause miscarriage. Rubella is not common due to widespread vaccination against the virus that causes it (the R component of the MMR vaccine). Doctors routinely test women for immunity against rubella as part of prenatal blood testing.

15 Sources
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Additional Reading

By Krissi Danielsson
Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage.