Bacterial Vaginosis During Pregnancy

Approximately 10% – 30% of pregnant women will experience bacterial vaginosis (BV) during their pregnancy. BV is characterized by a shift from a healthy vaginal microbiome – one dominated by acid-producing bacteria (the healthy bacteria, such as lactobacillus) – to a vagina dominated by unhealthy bacteria.

What are the symptoms of bacterial vaginosis during pregnancy?

The most prominent and often the most disconcerting symptom of BV is a strong fishy vaginal odor, but some women with BV also see increased amounts of discharge that is gray in color. A burning sensation when you urinate, itching in the vulvovaginal area and pain during sex are other symptoms of bacterial vaginosis.

How is BV diagnosed?

Vaginal discharge is tested through a wet mount (microscopic slide test), pH test (BV often causes a pH level of 4.5 or higher), KOH slide (microscopic slide test) or a whiff test (a mixture that causes a strong fishy odor).

What causes bacterial vaginosis?

Women with BV have reduced levels of amylase in the vagina, an enzyme that breaks up big carbohydrates into smaller carbohydrates called glycogen that healthy bacteria eat. Without this preferred food source, the friendly lactobacillus bacteria can’t grow and thrive. Women with BV also have reduced levels of antimicrobial peptides (AMPs) that can fight off invading bacteria. In healthy vaginas, vaginal mucosal cells normally make AMPs. It is not transmitted sexually, but it is associated with having vaginal sex. Therefore, it may be listed under sexually transmitted diseases when you research it.

You’re at increased risk if you:

  • Have new sex partners
  • Have more than one sex partner
  • Douche (use water or other liquid to clean inside the vagina)
  • Are pregnant
  • Are African-American. BV is twice as common in African-American women than in white women.
  • Used an intrauterine device (also called IUD)

How can this affect my pregnancy?

The U.S. Centers for Disease Control and Prevention (CDC) estimates that 1 million pregnant women get BV each year. Pregnant women are at increased risk for BV because of hormone changes that happen during pregnancy. Hormones are chemicals made by the body.

If you have BV during pregnancy, your baby is at increased risk for premature birth and low birthweight. Premature birth is birth before 37 weeks of pregnancy. Low birthweight is when your baby is born weighing less than 5 pounds, 8 ounces. Being born too early or too small can cause health problems for your baby.

BV also can cause pelvic inflammatory diseases (also called PID). PID is an infection in the uterus that can increase your risk for infertility (not being able to get pregnant).

If I am pregnant, will I be screened for bacterial vaginosis?

It is not necessary to screen non-symptomatic pregnant women for BV. When obtaining your prenatal care, you are not routinely screened for bacterial vaginosis. It is important that you discuss any concerns you may have about BV with your health care provider.

Why am I being screened for bacterial vaginosis?

The CDC advises that all pregnant women with symptoms of bacterial vaginosis be screened and treated. The CDC also supports screening women who have had previous preterm labor. Screening for BV is left up to your healthcare provider to decide.

What are the treatment options for bacterial vaginosis during pregnancy?

Antibiotics such as metronidazole (aka Flagyl), clindamycin, and tinidazole are often prescribed and will destroy some of the bacteria that cause symptoms of bacterial vaginosis. But, it is well-known that antibiotics kill off the good bacteria along with the infection-causing bacteria, which has potentially dire long-term impact on vaginal health. In a groundbreaking study published in Nature, Martin Blaser of New York University’s Langone Medical Center maintains that antibiotics’ impact on friendly bacteria is permanent. Blaser argues that the consequences of this are so serious that antibiotic prescriptions should not be given to pregnant women and young children.

Since vaginal health correlates to the presence of good bacteria, antibiotics must be used only when absolutely necessary. Killing off the good bacteria along with the bad can lead to vaginal imbalance and recurring instances of BV. Studies have shown that more than 50 percent of women treated for BV will experience a recurrence within 12 months. BV is most typically recurrent following a course of antibiotics.

Given that there are no easy answers when it comes to treating BV, the best course of action may very well be to help our vagina heal itself by putting the good bacteria back in charge. Options to try instead of antibiotics may include  a vaginal probiotic with healthy doses of micronutrients that are required for a healthy vaginal ecosystem (such as iron, zinc and manganese).

Research was done in 2004 by McDonald H, Brococklehurst P and Parsons J, suggests that antibiotic treatment may reduce the risk of premature rupture of membranes and low birth weight for women with a history of preterm labor and who have BV. This study did not find any significant evidence that treatment reduces premature labor.

How Can I Prevent Bacterial Vaginosis?

Healthy bacteria are the best defense against bacterial vaginosis, so anything you do to encourage the growth of lactobacillus bacteria will be a positive step forward in your fight against BV. First and foremost, don’t douche. Douching washes out all the good bacteria with the bad, and many douches contain harsh chemicals. When you are looking for vaginal health products to eliminate odor, maintain pH or lubricate for intimacy, choose products without glycerin (glycerol), coating oils, or parabens. It is also important to select products that are isotonic with vaginal cells, meaning that the salt/ion concentration of the product is the same as your vaginal tissues. Many lubricants and freshening gels have salt (ion) concentrations that are 4 times higher than vaginal fluids. High salt levels will pull water from cells and have been found to permanently damage vaginal mucosal cells and lactobacillus. Never use household oils such as coconut oil in your vagina. Coconut oil can contain toxic peroxides and inflammatory chemicals due to exposure to light and storage at room temperature, and can coat the vagina thereby interfering with vaginal self-cleaning.

A few additional comments about pH: remember that a healthy vaginal pH is acidic, with a pH level of 4.5. When choosing products for odor control or lubrication, be sure to select products that have a pH of no lower than 4 and no higher than about 5.5.

Want to Know More?

1Blaser MJ. Stop the killing of beneficial bacteria. Nature 476, 393–394 (25 August 2011). doi:10.1038/476393a
2Bradshaw CS, et al. (2006). “High recurrence rates of bacterial vaginosis over the course of 12 months after oral metronidazole therapy and factors associated with recurrence” J Infect Dis. 2006 Jun 1;193(11):1478-86.
3Nasioudis et al. Bacterial Vaginosis: A critical analysis of current knowledge. BJOG 2017;124:61-69