Bacterial vaginosis during pregnancy

Certain pregnancy problems are more common in women who have bacterial vaginosis than women who do not. It has been linked to miscarriage, preterm delivery (before 37 completed weeks of pregnancy), and pelvic infection after childbirth. Experts continue to research whether bacterial vaginosis is a direct or indirect cause.

Screening and treatment

Over the past few years, experts have found conflicting evidence that antibiotics for bacterial vaginosis may prevent preterm labor. Some recent reviews of studies suggest that antibiotics for bacterial vaginosis do not prevent preterm birth. But antibiotics do lower the risk of preterm premature rupture of membranes (pPROM), a condition that leads to preterm birth and sometimes infection. In women who have had a preterm birth before, treating bacterial vaginosis with antibiotics may also lower the risk of having a baby with a low birth weight.1

Despite mixed evidence, the U.S. Centers for Disease Control and Prevention (CDC) advises that all pregnant women with bacterial vaginosis symptoms be screened and treated with antibiotics. Based on some studies, the CDC also supports (but has no firm guidelines for) screening pregnant women who have no symptoms but who have had a preterm delivery in the past. This screening is best done during the first prenatal visit.2

Your doctor may screen you for bacterial vaginosis if you are pregnant or planning to become pregnant and have certain risk factors. These risk factors for preterm labor from infection include a history of:

  • Preterm delivery or pregnancy complications linked to infection, such as premature rupture of membranes (PROM).
  • Amniotic fluid infection.
  • Late miscarriage.
  • Low-birth-weight infant.
  • Endometritis after vaginal delivery or cesarean section.

If you are pregnant, are high-risk for preterm labor, and test positive for bacterial vaginosis, you will be treated with oral, not vaginal, antibiotics. Some doctors recommend that all pregnant women avoid vaginal treatment.

  • Studies show that oral antibiotics such as metronidazole and clindamycin are effective treatments that avoid increased risk to the fetus. 2
  • Use of clindamycin vaginal cream has been shown to have a slightly increased risk for preterm birth, so it is not recommended for use during pregnancy.3
  • Tinidazole is not recommended for use during pregnancy.

For pregnancy treatment, the CDC suggests retesting 1 month after treatment to check for the presence of infection.2


  1. McDonald HM, et al. (2007). Antibiotics for treating bacterial vaginosis in pregnancy. Cochrane Database of Systematic Reviews (1).
  2. Centers for Disease Control and Prevention (2006). Diseases characterized by vaginal discharge section of Sexually transmitted diseases treatment guidelines. MMWR, 55(RR-11): 49–56.
  3. Hillier S, et al. (2008). Bacterial vaginosis. In KK Holmes et al., eds., Sexually Transmitted Diseases, 4th ed., pp. 737–768. New York: McGraw-Hill.

Last Updated: February 18, 2010

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