Bacterial Vaginosis and Risk of Miscarriage

This common vaginal infection can cause problems during pregnancy

Sleeping woman holding pregnant belly
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You probably already know that bacteria are always present in your body. The good news is that many of these bacteria are "good" and serve an important purpose in keeping you healthy. Sometimes, however, too much harmful bacteria can lead to infection.

Bacterial vaginosis is a condition in which the normal balance of bacteria in the vagina is disturbed, leading to an overgrowth of bothersome species that overpower the usual beneficial species.


The condition can cause thin white or gray discharge from the vagina that has an unpleasant, potentially fish-like odor. Some women have burning during urination or genital itching, while other women can have bacterial vaginosis with no obvious symptoms.

Bacterial Vaginosis vs. Yeast Infection

Bacterial vaginosis is not the same thing as having a yeast infection. A yeast infection can cause itching but is more likely to cause a thick, white discharge. Yeast infections are caused by fungi, rather than by bacteria, so they are treated in an entirely different way. Also: Yeast infections have not been associated with a higher risk of miscarriage.

Incidence of Bacterial Vaginosis

Bacterial vaginosis is very common. A 2007 study found that almost 33% of women in a population survey were positive for bacterial vaginosis. The condition was more likely in women who douched and in certain ethnic groups.

The Centers for Disease Control and Prevention (CDC) reports that it's the most common vaginal infection in women ages 15 to 44. Having a new sexual partner or multiple sexual partners increases your risk for infection.


The usual treatment of bacterial vaginosis is antibiotics to kill the invading "bad" bacterial species.

Some researchers believe that applying yogurt to the vagina might also work as a treatment. Since the live bacteria in yogurt are similar to the bacteria that naturally inhabit the vagina, the idea is that applying yogurt may restore the natural bacterial balances. (But, of course, if you suspect that you have bacterial vaginosis, you should consult your doctor before taking any action.) It's important to treat BV, because the infection increases your chance of contracting sexually transmitted diseases, such as HIV, chlamydia, and gonorrhea, according to the CDC.

Risks During Pregnancy

Studies have found links between bacterial vaginosis and problems with pregnancy. For example, some studies have found that having a bacterial vaginosis infection increases the risk of having a low-birthweight infant (a baby that weighs less than 5.5 pounds) or delivering a preterm baby (before week 37 of gestation). 

In terms of miscarriage, numerous studies have found a link between bacterial vaginosis and second-trimester miscarriage (however, the condition does not appear to cause first-trimester miscarriage). Some doctors are starting to call for routine screenings of patients who are considered at high risk, but right now there are no recommendations to universally screen pregnant women for this condition.

If you are experiencing any of the BV symptoms listed above or if you have any suspicion that you may have bacterial vaginosis, be sure to mention this to your doctor—especially if you are pregnant. 


Allsworth, Jenifer E. and Jeffrey F. Peipert, "Prevalence of Bacterial Vaginosis." Obstetrics & Gynecology 2007. 

Center for Disease Control, "STD Facts - Bacterial Vaginosis (BV)." 22 Feb 2008. 

Llahi-Camp, J.M., R. Rai, C. Ison, L. Regan, and D. Taylor-Robinson, "Association of bacterial vaginosis with a history of second-trimester miscarriage." Human Reproduction 1996.

Oakeshott, Pippa, Phillip Hay, Sima Hay, Frances Steinke, Elizabeth Rink, and Sally Kerry, "Association between bacterial vaginosis or chlamydial infection and miscarriage before 16 weeks' gestation: prospective community-based cohort study. BMJ 2002. 

Svare, J.A., H. Schmidt, B.B. Hansen, and G. Lose, "Bacterial vaginosis in a cohort of Danish pregnant women: prevalence and relationship with preterm delivery, low birthweight, and perinatal infections." BJOG Dec 2006. 

Van Kessel, K., N. Asserfi, J. Marrazzo, and L. Eckert, "Common complementary and alternative therapies for yeast vaginitis and bacterial vaginosis: a systematic review." Obstetrics and Gynecology Survey May 2003.