Bacterial vaginosis is diagnosed in up to 23% of
pregnant women.1 This is a concern because
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.2 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 labour. Some recent reviews of studies suggest that
antibiotics for bacterial vaginosis do not prevent preterm
birth, but they do lower the risk of
preterm premature rupture of membranes (pPROM)—pPROM
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.3
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. The Society of Obstetricians and Gynaecologists of Canada (SOGC) supports (but has no firm guidelines for) screening pregnant women without symptoms who have had a preterm delivery in the past.4 This is best done during the
first prenatal visit.2
Your health professional 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 labour
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
caesarean section.
If you are pregnant, are high-risk for preterm
labour, 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. A longer course of treatment is more likely to be effective
than a shorter course.5
- 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.6
For pregnancy treatment, retesting 1 month after treatment to check for the presence of
infection is recommended.2