What is the recommended treatment for bacterial vaginosis (BV) in pregnancy?

Treatment of Bacterial Vaginosis in Pregnancy

All symptomatic pregnant women with BV should be treated with oral systemic therapy—specifically metronidazole 250 mg three times daily for 7 days OR clindamycin 300 mg twice daily for 7 days—to reduce the risk of adverse pregnancy outcomes including preterm birth, premature rupture of membranes, and postpartum endometritis. 1, 2

Treatment Regimens by Trimester

First Trimester

• While older guidelines suggested avoiding metronidazole in the first trimester, multiple studies and meta-analyses have not demonstrated consistent associations between metronidazole use during pregnancy and teratogenic or mutagenic effects in newborns 1, 2
• If there is concern about first trimester metronidazole use, clindamycin 300 mg orally twice daily for 7 days is an acceptable alternative 2
• Avoid clindamycin vaginal cream during pregnancy, as evidence from three trials suggests increased adverse events (prematurity and neonatal infections) after use of topical clindamycin preparations 1

Second and Third Trimesters

• Metronidazole 250 mg orally three times daily for 7 days is the preferred regimen 1, 2
• Alternative: Clindamycin 300 mg orally twice daily for 7 days 1, 2

Critical Treatment Principles

Why Systemic Therapy is Essential

• Systemic (oral) therapy is strongly preferred over topical agents during pregnancy to treat possible subclinical upper genital tract infections 1, 2
• Topical metronidazole gel and clindamycin cream should NOT be used in pregnancy due to inadequate treatment of upper tract disease and evidence of harm with clindamycin cream 1

Risk Stratification Matters

High-Risk Pregnant Women (history of prior preterm delivery):

• Screen and treat at the first prenatal visit or earliest part of second trimester 1, 2
• Treatment with recommended regimens has reduced preterm delivery in 3 of 4 randomized controlled trials 1
• Follow-up evaluation 1 month after treatment completion should be considered to evaluate treatment effectiveness 1

Low-Risk Pregnant Women (no history of preterm delivery):

• Treat all symptomatic women 1, 2
• Data are conflicting regarding treatment of asymptomatic low-risk women, but some trials showed reduction in spontaneous preterm birth and postpartum infectious complications 1

Important Caveats and Pitfalls

Dosing Considerations

• The 250 mg three-times-daily metronidazole regimen used in pregnancy trials differs from the 500 mg twice-daily regimen used in non-pregnant women 1
• Some specialists recommend the higher 500 mg twice-daily dose for pregnant women, though this was not the regimen studied in pregnancy trials 1
• Single-dose or short-course metronidazole regimens (2g doses) were NOT effective in reducing preterm birth and should be avoided in pregnancy 1

What NOT to Do

• Do not use metronidazole vaginal gel - inadequate for treating upper tract infection 1, 2
• Do not use clindamycin vaginal cream - associated with increased adverse neonatal outcomes 1, 2
• Do not treat male sex partners - this does not affect treatment response or recurrence rates 1, 2

Patient Counseling

• Advise patients to avoid alcohol during metronidazole treatment and for 24 hours afterward due to potential disulfiram-like reaction 2, 3, 4
• Follow-up visits are unnecessary if symptoms resolve, except in high-risk women where follow-up at 1 month may be warranted 1, 2

Clinical Context

BV in pregnancy is associated with serious adverse outcomes including premature rupture of membranes, chorioamnionitis, preterm labor, preterm birth, postpartum endometritis, and post-cesarean wound infection 1, 2, 5. The goal of treatment is not just symptom relief but prevention of these complications, which is why systemic therapy targeting potential upper tract involvement is essential.