Treatment of Asymptomatic Bacterial Vaginosis in Pregnancy
Routine treatment of asymptomatic bacterial vaginosis in average-risk pregnant women is NOT recommended, as screening and treatment do not improve outcomes such as preterm labor or preterm birth. 1
Risk Stratification Determines Management
The approach to asymptomatic BV in pregnancy depends entirely on preterm birth risk:
Average-Risk Pregnant Women (No Prior Preterm Birth)
- Do not screen or treat asymptomatic BV 1
- Good evidence demonstrates that screening and treatment in average-risk asymptomatic pregnant women do not improve outcomes 1
- The U.S. Preventive Services Task Force gives this a D recommendation (recommends against routine screening) 1
- Treatment has not been shown to reduce preterm birth risk in this population 2, 3
High-Risk Pregnant Women (History of Prior Preterm Delivery)
- Screening for BV is an option in women with previous preterm delivery 1
- Treatment may reduce the risk of preterm birth in this specific high-risk population 4, 3
- However, a single previous episode of preterm delivery alone may not reliably identify women who will benefit 1
- Studies showing benefit were performed in populations with especially high risk (35-57%) of preterm birth 1
When Treatment IS Indicated for Asymptomatic BV
Treatment should be given in these specific circumstances:
- Before surgical abortion procedures to reduce post-abortion pelvic inflammatory disease 4
- Before hysterectomy due to increased risk of postoperative infectious complications 4
- Before other invasive gynecological procedures (endometrial biopsy, IUD placement) where BV increases risk of endometritis, PID, and vaginal cuff cellulitis 4
Treatment Regimens (If Treatment Is Indicated)
Preferred Options:
- Oral metronidazole 500 mg twice daily for 7 days (95% cure rate) 5, 4
- Metronidazole gel 0.75%, one full applicator (5g) intravaginally once daily for 5 days 5, 4
- Clindamycin cream 2%, one full applicator (5g) intravaginally at bedtime for 7 days 5, 4
Alternative Options:
- Oral metronidazole 2g single dose (lower 84% cure rate, use only if compliance is a concern) 5, 4
- Oral clindamycin 300 mg twice daily for 7 days 5, 4
Timing and Follow-Up Considerations
- Optimal screening time for high-risk women is second trimester (13-24 weeks of pregnancy) 1
- Follow-up evaluation one month after treatment completion is recommended in pregnant women to verify cure, due to the possibility of adverse pregnancy outcomes 1
- Follow-up is unnecessary if no symptoms develop in asymptomatic cases 4
Important Treatment Precautions
- Avoid alcohol during metronidazole treatment and for 24 hours afterward due to potential disulfiram-like reaction 5, 4
- Clindamycin cream is oil-based and may weaken latex condoms and diaphragms 5, 4
- Do not treat male sex partners as routine treatment has not been shown to reduce recurrence rates 4
Critical Evidence Nuances
The evidence on treating asymptomatic BV in pregnancy is notably mixed:
- A 2016 systematic review using GRADE methodology gave a strong recommendation AGAINST treatment with metronidazole in both high-risk and low-risk pregnancies (RR 1.11 for low-risk, RR 0.96 for high-risk) 2
- A 2013 Cochrane review found antibiotic treatment did not reduce PTB before 37 weeks overall (RR 0.88), but when screening criteria were broadened to include women with abnormal flora (intermediate flora or BV), treatment reduced PTB risk by 47% (RR 0.53) 6
- The most recent guidelines (2025) acknowledge this controversy but suggest considering treatment only in truly high-risk women with prior preterm delivery 4
Common Pitfalls to Avoid
- Do not routinely screen all pregnant women for asymptomatic BV—evidence shows no benefit in average-risk populations 1
- Do not assume treatment prevents preterm birth in all populations—benefit is limited to specific high-risk groups, if present at all 2, 3
- Do not use short-course regimens in pregnancy—7-day courses are standard 5