Skip to navigation bar Skip to breadcrumbs Skip to page content Skip to comments area
clear place holder
Envelope icon E-mail Updates Teal square Text size:  a A A
You are here: HomePublic Comments and NominationsOpportunity for Public CommentDraft Recommendation Statement : Draft Recommendation Statement

Draft Recommendation Statement

Bacterial Vaginosis in Pregnant Persons to Prevent Preterm Delivery: Screening

This opportunity for public comment expires on November 4, 2019 at 8:00 PM EST

Note: This is a Draft Recommendation Statement. This draft is distributed solely for the purpose of receiving public input. It has not been disseminated otherwise by the USPSTF. The final Recommendation Statement will be developed after careful consideration of the feedback received and will include both the Research Plan and Evidence Review as a basis.

Recommendations made by the USPSTF are independent of the U.S. government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.

Draft: Recommendation Summary

PopulationRecommendationGrade
(What's This?)
Pregnant persons not at increased risk for preterm delivery

The USPSTF recommends against screening for bacterial vaginosis (BV) in pregnant persons who are not at increased risk for preterm delivery. 

D
Pregnant persons at increased risk for preterm delivery

The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for BV in pregnant persons who are at increased risk for preterm delivery. 

I

See the “Practice Considerations” section for additional information on risk assessment and suggestions for practice regarding the I statement.

Send Us Your Comments

In an effort to maintain a high level of transparency in our methods, we open our draft Recommendation Statements to a public comment period before we publish the final version.

Leave a Comment >>

Draft: Importance

BV is common and is caused by a disruption of the microbiological environment in the lower genital tract. In the United States, reported BV prevalence among pregnant women ranges from 5.8% to 19.3%, and is higher in some races/ethnicities.1 BV during pregnancy has been associated with adverse obstetrical outcomes including preterm delivery,2 early miscarriage,3 postpartum endometritis,4 and low birth weight.5 BV is often asymptomatic, can resolve spontaneously, and recurs often with and without treatment.6 Most clinicians treat symptomatic BV in pregnancy.

In the United States, approximately 10% of live births are preterm.7 Preterm birth is associated with serious complications, including major intraventricular hemorrhage, acute respiratory illnesses, and sepsis.7-10 Approximately two-thirds of all infant deaths in the United States occur among infants born preterm.8 The frequency and severity of adverse outcomes from preterm delivery are higher with earlier gestational age.

Draft: Assessment of Magnitude of Net Benefit

The USPSTF concludes with moderate certainty that screening for asymptomatic BV in pregnant persons not at increased risk for preterm delivery has no net benefit in preventing preterm delivery.

The USPSTF concludes that for pregnant persons at increased risk for preterm delivery, the evidence is conflicting, and the balance of benefits and harms cannot be determined.

See the Table for more information on the USPSTF recommendation rationale and assessment. For more details on the methods the USPSTF uses to determine the net benefit, see the USPSTF Procedure Manual.11

Draft: Practice Considerations

Patient Population Under Consideration

This recommendation statement applies to pregnant persons without symptoms of BV.

Definition

Healthy vaginal flora is comprised of more than 90% lactobacilli. BV occurs when there is a shift in this flora to include a greater proportion of mixed anaerobic bacteria, such as the Gardnerella, Prevotella, and Atopobium species.12, 13 Most often, BV is asymptomatic. When symptoms occur, they include off-white, thin, homogenous discharge or a vaginal “fishy” odor.

Assessment of Risk

Persons who are not at increased risk for preterm delivery include pregnant persons with no history of previous preterm delivery or other risk factors for preterm delivery. While multiple factors increase risk for preterm delivery, one of the strongest risk factors is prior preterm delivery.

See the “Potential Preventable Burden” section below for additional information on risk factors for preterm delivery.

Screening Tests

Screening tests for BV are performed on vaginal secretions obtained during a pelvic examination in a primary care setting. Available screening tests include nucleic acid assays, sialidase assays, and clinical assessment (i.e., using Amsel’s criteria of pH, vaginal discharge, clue cells, and “whiff test”).

Treatment

Oral metronidazole and oral clindamycin, as well as vaginal metronidazole gel or clindamycin cream, are the usual treatments for symptomatic BV. The optimal treatment regimen for pregnant persons with BV is unclear. The Centers for Disease Control and Prevention website provides current treatment recommendations.14

Suggestions for Practice Regarding the I Statement

Potential Preventable Burden

BV occurs in as many as 29% of women in the United States,15 and in 5.8% to 19.3% of pregnant women, depending on the specific population being studied.1, 16 Reported factors that increase the likelihood of a diagnosis of BV include African American race, poverty, smoking, increased body mass index, vaginal douching, low educational attainment, and certain sexual behaviors, including a high number of partners, lack of condom or contraceptive use, vaginal sex, sex with a female partner, and concurrent sexually transmitted infections.6, 15, 17, 18

Causes of preterm delivery are likely multifactorial, and numerous risk factors are associated with an increased risk for preterm birth.6 History of a prior preterm delivery is associated with a 2.5-fold increased odds for preterm delivery in subsequent pregnancies.19 While BV during pregnancy is associated with a 2-fold increased odds for preterm delivery,2 it is not clear that BV is a cause of preterm delivery. Other additional risk factors for preterm delivery include, but are not limited to, cervical insufficiency, multiple gestation, young or advanced maternal age, low maternal body mass index (<20 kg/m2), genitourinary infections, HIV infection, and other maternal medical conditions.6, 20-23 The association of these additional risk factors with preterm delivery is small to moderate, and factors can act in isolation or in combination. Preterm birth rates also vary by race/ethnicity in the United States; recent data report preterm birth rates of 8.6% among Asian women, 11.8% among Native Hawaiian/Other Pacific Islander women, 9.7% among Hispanic women, 11.5% among American Indian/Alaska Native women, 14.1% among black women, and 9.1% among white women.7 Among women with a prior preterm delivery, the rate of recurrent preterm delivery in African American women is 4 times higher than the rate of recurrent preterm delivery among white women.20 Even when these risk factors are present, it is unclear whether screening and treating asymptomatic BV in pregnant persons at increased risk for preterm delivery prevents preterm delivery.

African American race is both associated with BV and strongly associated with preterm delivery. Other factors associated with both BV and preterm delivery include young age, nulliparity, current tobacco use, low educational attainment, lower income, and concurrent sexually transmitted infections.

Five studies provided evidence on the benefit of treatment of BV in women with a previous preterm delivery for reducing the incidence of preterm delivery. Four of these studies evaluated the treatment of BV with oral metronidazole6 and reported the incidence of preterm delivery at less than 37 weeks. Three of these studies reported an absolute reduction in preterm delivery with treatment (ranging from 18% to 29% risk difference), but limitations of the evidence, including imprecision, the fact that some of the results were from subgroup analyses, and the inconsistency of results, prevented a definitive conclusion about the benefit.6 Two studies (one evaluating oral metronidazole and the other evaluating vaginal clindamycin) presented results for preterm delivery at less than 34 weeks, and the results were mixed.6

Potential Harms

The harms of screening for BV in pregnant persons and treatment with antibiotics generally involve minor side effects for women such as gastrointestinal upset and vaginal candidiasis.6 Two large meta-analyses of observational studies on the use of metronidazole during pregnancy for any reason (not limited to BV) reported no increase in congenital malformations in children exposed in utero.24, 25

Current Practice

No data are available on how frequently pregnant persons at increased risk for preterm delivery are screened for BV during pregnancy, but screening is not recommended by any large U.S. professional organization. Clinicians routinely treat pregnant persons for symptomatic BV.

Other Related USPSTF Recommendations

The USPSTF has also issued recommendations on screening for asymptomatic bacteriuria in adults and screening for syphilis in pregnant persons.

Draft: Update of Previous USPSTF Recommendation

The USPSTF last issued a recommendation on this topic in 2008. Although newer evidence was reviewed, the recommendations have essentially remained the same. The language used to describe a pregnant person’s risk for preterm delivery has been updated to be more consistent with other current USPSTF recommendations.

Draft: Supporting Evidence

Scope of Review

To update its 2008 recommendation, the USPSTF commissioned a systematic review6 to evaluate the accuracy of screening and the benefits and harms of screening for and treatment of BV in asymptomatic pregnant persons.

Accuracy of Screening Tests

The USPSTF reviewed evidence from 25 cross-sectional studies that reported on test accuracy of the BD Affirm™ VPIII Test (Becton, Dickinson and Co., Franklin Lakes, NJ), BD Max™ System, OSOM® BVBLUE® Test (Sekisui Diagnostics, Burlington, MA), and Amsel’s clinical criteria to diagnose BV.6 The vast majority of studies were conducted in nonpregnant and symptomatic women; only two studies were conducted exclusively in asymptomatic pregnant women, and two additional studies were conducted in symptomatic pregnant women. None of the available evidence indicated that accuracy would differ between pregnant and nonpregnant populations. Studies were conducted in a variety of settings, including academic, hospital-based outpatient, or community obstetrics-gynecology clinics; sexually transmitted infection and family planning clinics; local health department clinics; and longitudinal cohorts; most (13 studies) were conducted in the United States.

Pooled sensitivity and specificity of the BD Affirm VPIII test was 0.87 (95% CI, 0.80 to 0.92) and 0.81 (95% CI, 0.73 to 0.88), respectively (five studies; n=2,936).6 Only one study (n=1,338) reported accuracy of the BD Max System; sensitivity was 0.93 (95% CI, 0.91 to 0.94) and specificity was 0.92 (95% CI, 0.90 to 0.94).6 Three studies reported accuracy of the OSOM BVBLUE Test (n=864), and sensitivity ranged from 0.61 to 0.92 and specificity ranged from 0.86 to 0.99.6 Fifteen studies (n=7,171) reported on accuracy of complete Amsel’s criteria (having at least three of the following four criteria to detect BV: vaginal pH >4.5, presence of clue cells, thin homogeneous discharge, and a positive whiff test [an amine, “fishy” odor when potassium hydroxide is added to vaginal discharge]). Pooled sensitivity and specificity from 14 of those studies were 0.76 (95% CI, 0.63 to 0.85) and 0.95 (95% CI, 0.89 to 0.98), respectively.6 Five studies (n=2,674) reported on the accuracy of using modified Amsel’s criteria (having at least two of the following three criteria to detect BV: presence of clue cells, thin homogeneous discharge, and a positive “whiff” test). Pooled sensitivity and specificity from four studies was 067 (95% CI, 0.54 to 0.78) and 0.96 (95% CI, 0.93 to 0.98), respectively.6

Benefits of Early Detection and Treatment

No studies were identified that directly evaluated the benefit of screening for BV in asymptomatic pregnant persons on reducing preterm delivery and related morbidity and mortality.6

The USPSTF reviewed evidence from 13 randomized, controlled trials that reported on the effect of treatment of asymptomatic BV in pregnant women on preterm delivery and related morbidity.6 Most studies enrolled pregnant women in their second trimester of pregnancy. Ten trials targeted a general obstetric population and enrolled participants without regard to risk for preterm delivery.6, 26-35 Zero percent to 10.9% of participants in these trials had a history of prior preterm delivery, and two of these trials reported results by subgroup of participants who had a history of prior preterm delivery. Three additional trials specifically targeted pregnant women who had a history of prior preterm delivery.6, 36-38 Of the seven trials that reported information on race/ethnicity of participants, the percentage of participants who were nonwhite ranged from 2% to 85%. Four trials were conducted in the United States; the others were conducted in Europe and Australia. Interventions evaluated included oral metronidazole (three trials), oral metronidazole plus erythromycin (one trial), oral clindamycin (two trials), and intravaginal clindamycin (seven trials).

Findings from trials targeting a general obstetric population were largely consistent in reporting no benefit across a variety of preterm delivery outcomes. No statistically significant reduction was found in all-cause preterm delivery prior to 37 weeks (pooled relative risk [RR], 1.02 [95% CI, 0.86 to 1.20%]; six studies; n=6,307), spontaneous preterm delivery prior to 37 weeks (pooled RR, 0.78 [95% CI, 0.56 to 1.07]; eight studies; n=7,571), preterm delivery prior to 32 weeks (pooled RR, 0.87 [95% CI, 0.54 to 1.42]; three studies; n=5,564), birth weight <2,500 g (pooled RR, 1.03 [95% CI, 0.83 to 1.29]; five studies; n=5,377), birth weight <1,500 g (pooled RR, 1.05 [95% CI, 0.50 to 2.18]; three studies; n=5,149), or premature rupture of membranes (PROM) or preterm premature rupture of membranes (PPROM) (pooled RR, 1.11 [95% CI, 0.72 to 1.72]; four studies; n=3,568).6

Findings from the five trials reporting outcomes for women with a history of prior preterm delivery were inconsistent. Four trials (n=451) reported on preterm delivery prior to 37 weeks in women with a history of prior preterm delivery.6 RRs ranged from 0.17 to 1.33, although three of the studies had statistically significant findings favoring treatment.6 Two trials (n=102) reported on preterm delivery prior to 34 weeks in women with a history of prior preterm delivery. RRs were 1.00 (95% CI, 0.07 to 14.05) in one study and 0.41 in the other study (95% CI, 0.08 to 2.11).6

Harms of Screening and Treatment

No studies that directly evaluated the harms of screening for BV in pregnancy were identified.

The USPSTF reviewed evidence on harms of treatment of BV during pregnancy from eight randomized, controlled trials that reported on maternal harms, and four observational studies and two meta-analyses of observational studies that reported on harms to children from in utero exposure.

The eight trials that reported on maternal harms of treatment of BV during pregnancy also reported on benefits of treatment, so study characteristics are described above. Four trials26, 27, 33, 38 (n=1,718) reported on adverse events from intravaginal clindamycin. No serious adverse events were reported. Minor side effects such as vaginal candidiasis, troublesome discharge, and study withdrawal because of itching were reported infrequently and at similar rates between intervention and control groups. Maternal harms of oral clindamycin were reported in two trials29, 32 (n=3,345). Only one trial reported on serious adverse events and did not observe any in either treatment group. Both studies reported a higher incidence of stopping medication in the oral clindamycin group, although findings were statistically significant in only one study. Maternal harms of oral metronidazole were reported in two trials30, 31 (n=2,776). A higher incidence of adverse events was reported with oral metronidazole in both studies, although the finding was only statistically significant in one study.

Three observational studies39-41 (n=62,271) and two meta-analyses24, 25 (n >199,541) reported on congenital malformations among children exposed to metronidazole in utero for any clinical indication (not just BV). The studies included in this body of evidence dated back to the 1960s to 1990s; the three observational studies were based on registry data from Denmark, Hungary, and Israel. None reported any significant increase in congenital malformations. A single observational study (n=328,846) of Tennessee’s Medicaid program reported on cancer incidence before age 5 years among children who were exposed to metronidazole in utero, and no significant increase with exposure was observed.42

Overall, the USPSTF found few reported maternal harms and no reported fetal harms in the literature. In addition, use of metronidazole and clindamycin to treat BV during pregnancy has become the standard of care, with no signal of significant maternal or fetal adverse effects to date.

How Does Evidence Fit With Biological Understanding?

Causes of preterm delivery are likely multifactorial, and the exact mechanism of how some risk factors may lead to preterm delivery is poorly understood. Epidemiologic data suggest that risk for preterm delivery may double when asymptomatic BV is present (pooled odds ratio, 2.16 [95% CI, 1.56 to 3.00]; 32 studies; 30,518 participants).2 However, the causal pathway of how BV may lead to preterm delivery is unclear. Earlier theories postulated that BV may lead to upper genital tract infections, which may in turn contribute to PPROM or preterm labor. More recently, it has been suggested that maternal vaginal mucosal immune response may play a role in preterm labor or PPROM, as well as acquisition of BV. Although the evidence is clear that treating asymptomatic BV in pregnant persons not at increased risk for preterm delivery does not prevent preterm delivery, it is still unclear whether treating asymptomatic pregnant persons at increased risk for preterm delivery may help prevent preterm delivery.

Draft: Research Needs and Gaps

More studies are needed to evaluate screening for and treatment of asymptomatic BV in pregnant persons at increased risk for preterm delivery. These studies should:

  • Include pregnant persons with a history of prior preterm delivery, as well as other risk factors for preterm delivery, such as cervical insufficiency, multiple gestations, young or advanced maternal age, low maternal body mass index (<20 kg/m2), and African American, Native Hawaiian/Other Pacific Islander, or American Indian/Alaska Native race/ethnicity.
  • Be adequately powered to detect a reduction of all-cause preterm delivery prior to 37 weeks of gestation.

If a reduction in preterm delivery is found with treatment of asymptomatic BV in pregnant persons at increased risk for preterm delivery, then additional research is needed on ways to better identify persons at increased risk for preterm delivery.

Draft: Recommendations of Others

Most organizations in the United States do not recommend screening for BV in asymptomatic pregnant women. The American College of Obstetricians and Gynecologists states that several specific screening tests, including testing for BV, have been proposed to assess a woman’s risk of preterm delivery; however, intervention studies based on these screening tests in asymptomatic women (for preterm delivery) have not demonstrated improved perinatal outcomes, thus the American College of Obstetricians and Gynecologists does not recommend their use as a screening strategy.43 The Centers for Disease Control and Prevention states that “Evidence does not support routine screening for bacterial vaginosis in asymptomatic pregnant women at high risk for preterm delivery. Symptomatic women should be evaluated and treated.”44 The American Academy of Family Physicians endorses the 2008 USPSTF recommendation on screening for BV.45

Send Us Your Comments

In an effort to maintain a high level of transparency in our methods, we open our draft Recommendation Statements to a public comment period before we publish the final version.

Leave a Comment >>

References:

1. Kenyon C, Colebunders R, Crucitti T. The global epidemiology of bacterial vaginosis: a systematic review. Am J Obstet Gynecol. 2013;209(6):505-523.
2. Leitich H, Kiss H. Asymptomatic bacterial vaginosis and intermediate flora as risk factors for adverse pregnancy outcome. Best Pract Res Clin Obstet Gynaecol. 2007;21(3):375-390.
3. McGregor JA, French JI, Parker R, et al. Prevention of premature birth by screening and treatment for common genital tract infections: results of a prospective controlled evaluation. Am J Obstet Gynecol. 1995;173(1):157-167.
4. Watts DH, Krohn MA, Hillier SL, Eschenbach DA. Bacterial vaginosis as a risk factor for post-cesarean endometritis. Obstet Gynecol. 1990;75(1):52-58.
5. Hillier SL, Nugent RP, Eschenbach DA, et al. Association between bacterial vaginosis and preterm delivery of a low-birth-weight infant. N Engl J Med. 1995;333(26):1737-1742.
6. Kahwati LC CR, Berkman ND, Urrutia R, Patel SV, Zeng J, Viswanathan M. Screening for Bacterial Vaginosis in Pregnant Adolescents and Women to Prevent Preterm Delivery: An Updated Systematic Review for the U.S. Preventive Services Task Force. Evidence Synthesis No. 190. AHRQ Publication No. 19-05259-EF-1. Rockville, MD: Agency for Healthcare Research and Quality; 2019.
7. Hamilton BE, Martin JA, Osterman MJ, Rossen LM. Births: Provisional Data for 2018. Vital Statistics Rapid Release; no. 7. Hyattsville, MD: National Center for Health Statistics; 2019. https://www.cdc.gov/nchs/data/vsrr/vsrr-007-508.pdf. Accessed September 18, 2019.
8. Mathews T, MacDorman MF, Thoma ME. Infant mortality statistics from the 2013 period linked birth/infant death data set. Natl Vital Stat Rep. 2015;64(9):1-30.
9. Schindler T, Koller-Smith L, Lui K, Bajuk B, Bolisetty S. Causes of death in very preterm infants cared for in neonatal intensive care units: a population-based retrospective cohort study. BMC Pediatr. 2017;17(1):59.
10. McIntire DD, Leveno KJ. Neonatal mortality and morbidity rates in late preterm births compared with births at term. Obstet Gynecol. 2008;111(1):35-41.
11. U.S. Preventive Services Task Force. Procedure Manual. https://www.uspreventiveservicestaskforce.org/Page/Name/procedure-manual. Accessed September 18, 2019.
12. Srinivasan S, Fredricks DN. The human vaginal bacterial biota and bacterial vaginosis. Interdiscip Perspect Infect Dis. 2008;2008.
13. Livengood CH. Bacterial vaginosis: an overview for 2009. Rev Obstet Gynecol. 2009;2(1):28-37.
14. Centers for Disease Control and Prevention. Bacterial vaginosis treatment and care. https://www.cdc.gov/std/bv/treatment.htm. Accessed September 18, 2019.
15. Allsworth JE, Peipert JF. Prevalence of bacterial vaginosis: 2001-2004 National Health and Nutrition Examination Survey data. Obstet Gynecol. 2007;109(1):114-120.
16. Lamont RF, Sobel JD, Akins RA, et al. The vaginal microbiome: new information about genital tract flora using molecular based techniques. BJOG. 2011;118(5):533-549.
17. Vodstrcil LA, Walker SM, Hocking JS, et al. Incident bacterial vaginosis (BV) in women who have sex with women is associated with behaviors that suggest sexual transmission of BV. Clin Infect Dis. 2015;60(7):1042-1053.
18. Schwebke JR, Desmond R. Risk factors for bacterial vaginosis in women at high risk for sexually transmitted diseases. Sex Transm Dis. 2005;32(11):654-658.
19. Mercer BM, Goldenberg RL, Moawad AH, et al. The preterm prediction study: effect of gestational age and cause of preterm birth on subsequent obstetric outcome. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Am J Obstet Gynecol. 1999;181(5 Pt 1):1216-1221.
20. Muglia LJ, Katz M. The enigma of spontaneous preterm birth. N Engl J Med. 2010;362(6):529-535.
21. Goldenberg RL, Culhane JF, Iams JD, Romero R. Epidemiology and causes of preterm birth. Lancet. 2008;371(9606):75-84.
22. Institute of Medicine. Preterm Birth: Causes, Consequences, and Prevention. Washington DC: National Academies Press; 2007.
23. Slyker JA, Patterson J, Ambler G, et al. Correlates and outcomes of preterm birth, low birth weight, and small for gestational age in HIV-exposed uninfected infants. BMC Pregnancy Childbirth. 2014;14:7.
24. Burtin P, Taddio A, Ariburnu O, Einarson TR, Koren G. Safety of metronidazole in pregnancy: a meta-analysis. Am J Obstet Gynecol. 1995;172(2 Part 1):525-529.
25. Caro-Paton T, Carvajal A, Martin de Diego I, Martin-Arias LH, Alvarez Requejo A, Rodriguez Pinilla E. Is metronidazole teratogenic? A meta-analysis. Br J Clin Pharmacol. 1997;44(2):179-182.
26. Kekki M, Kurki T, Pelkonen J, Kurkinen-Raty M, Cacciatore B, Paavonen J. Vaginal clindamycin in preventing preterm birth and peripartal infections in asymptomatic women with bacterial vaginosis: a randomized, controlled trial. Obstet Gynecol. 2001;97(5 Pt 1):643-648.
27. Kiss H, Petricevic L, Husslein P. Prospective randomised controlled trial of an infection screening programme to reduce the rate of preterm delivery. BMJ. 2004;329(7462):371.
28. Lamont RF, Duncan SL, Mandal D, Bassett P. Intravaginal clindamycin to reduce preterm birth in women with abnormal genital tract flora. Obstet Gynecol. 2003;101(3):516-522.
29. Ugwumadu A, Manyonda I, Reid F, Hay P. Effect of early oral clindamycin on late miscarriage and preterm delivery in asymptomatic women with abnormal vaginal flora and bacterial vaginosis: a randomised controlled trial. Lancet. 2003;361(9362):983-988.
30. Carey JC, Klebanoff MA, Hauth JC, et al. Metronidazole to prevent preterm delivery in pregnant women with asymptomatic bacterial vaginosis. National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units. N Engl J Med. 2000;342(8):534-540.
31. McDonald HM, O'Loughlin JA, Vigneswaran R, et al. Impact of metronidazole therapy on preterm birth in women with bacterial vaginosis flora (Gardnerella vaginalis): a randomised, placebo controlled trial. Br J Obstet Gynaecol. 1997;104(12):1391-1397.
32. Subtil D, Brabant G, Tilloy E, et al. Early clindamycin for bacterial vaginosis in pregnancy (PREMEVA): a multicentre, double-blind, randomised controlled trial. Lancet. 2018;392(10160):2171-2179.
33. Larsson PG, Fåhraeus L, Carlsson B, Jakobsson T, Forsum U; Premature Study Group of the Southeast Health Care Region of Sweden. Late miscarriage and preterm birth after treatment with clindamycin: a randomised consent design study according to Zelen. BJOG. 2006;113(6):629-637.
34. Guaschino S, Ricci E, Franchi M, et al. Treatment of asymptomatic bacterial vaginosis to prevent pre-term delivery: a randomised trial. Eur J Obstet Gynecol Reprod Biol. 2003;110(2):149-152.
35. McGregor JA, French JI, Jones W, et al. Bacterial vaginosis is associated with prematurity and vaginal fluid mucinase and sialidase: results of a controlled trial of topical clindamycin cream. Am J Obstet Gynecol. 1994;170(4):1048-1060.
36. Hauth JC, Goldenberg RL, Andrews WW, DuBard MB, Copper RL. Reduced incidence of preterm delivery with metronidazole and erythromycin in women with bacterial vaginosis. N Engl J Med. 1995;333(26):1732-1736.
37. Morales WJ, Schorr S, Albritton J. Effect of metronidazole in patients with preterm birth in preceding pregnancy and bacterial vaginosis: a placebo-controlled, double-blind study. Am J Obstet Gynecol. 1994;171(2):345-347; discussion 348-349.
38. Vermeulen GM, Bruinse HW. Prophylactic administration of clindamycin 2% vaginal cream to reduce the incidence of spontaneous preterm birth in women with an increased recurrence risk: a randomised placebo-controlled double-blind trial. Br J Obstet Gynaecol. 1999;106(7):652-657.
39. Sorensen HT, Larsen H, Jensen ES, et al. Safety of metronidazole during pregnancy: a cohort study of risk of congenital abnormalities, preterm delivery and low birth weight in 124 women. J Antimicrob Chemother. 1999;44(6):854-856.
40. Diav-Citrin O, Shechtman S, Gotteiner T, Arnon J, Ornoy A. Pregnancy outcome after gestational exposure to metronidazole: a prospective controlled cohort study. Teratology. 2001;63(5):186-192.
41. Czeizel AE, Rockenbauer M. A population based case-control teratologic study of oral metronidazole treatment during pregnancy. Br J Obstet Gynaecol. 1998;105(3):322-327.
42. Thapa PB, Whitlock JA, Brockman Worrell KG, et al. Prenatal exposure to metronidazole and risk of childhood cancer: a retrospective cohort study of children younger than 5 years. Cancer. 1998;83(7):1461-1468.
43. American College of Obstetricians and Gynecologists. Practice bulletin no. 130: prediction and prevention of preterm birth. Obstet Gynecol. 2012;120(4):964-973.
44. Workowski KA, Bolan GA. Sexually Transmitted Diseases Treatment Guidelines, 2015. MMWR Morb Mortal Wkly Rep. 2015;64(3);1-137.
45. American Academy of Physicians. Clinical preventive service recommendation: bacterial vaginosis. https://www.aafp.org/patient-care/clinical-recommendations/all/bacterial-vaginosis.html. Accessed September 18, 2019.

Draft: Table. Summary of USPSTF Rationale

Rationale Pregnant Persons Not at Increased Risk for Preterm Delivery Pregnant Persons at Increased Risk for Preterm Delivery
Detection There is adequate evidence that currently available tests can accurately identify bacterial vaginosis in pregnant persons.
Benefits of early detection and intervention and treatment
  • There is inadequate direct evidence on the benefits of screening for asymptomatic BV in pregnant persons to reduce adverse health outcomes.
  • There is adequate evidence that treatment of asymptomatic BV with antibiotics in pregnant persons not at increased risk for preterm delivery does not provide a benefit in reducing adverse health outcomes.
  • There is inadequate direct evidence on the benefits of screening for asymptomatic BV in pregnant persons to reduce adverse health outcomes.
  • There is inadequate evidence to determine whether treatment of asymptomatic BV in persons at increased risk for preterm delivery provides a benefit in reducing adverse health outcomes (because of the limited number of studies, conflicting and imprecise results, heterogeneity of studies, and other limitations of the study designs)
Harms of early detection and intervention and treatment
  • There is inadequate direct evidence on the harms of screening for BV in pregnant persons.
  • There is adequate evidence that treatment of BV in pregnant persons results in small maternal harms, including vaginal candidiasis and gastrointestinal upset, and no harms to the fetus.
  • Overall, there is adequate evidence to bound the harms of screening for and treatment of BV in pregnant persons as no greater than small, based on the false-positives from screening and the reported minor side effects from treatment with antibiotics.
USPSTF Assessment The USPSTF concludes with moderate certainty that screening for asymptomatic BV in pregnant persons not at increased risk for preterm delivery has no net benefit. The USPSTF concludes that the evidence is conflicting, and the balance of benefits and harms of screening for asymptomatic BV in pregnant persons at increased risk for preterm delivery cannot be determined.
Current as of: October 2019

Internet Citation: Draft Recommendation Statement: Bacterial Vaginosis in Pregnant Persons to Prevent Preterm Delivery: Screening. U.S. Preventive Services Task Force. October 2019.
https://www.uspreventiveservicestaskforce.org/Page/Document/draft-recommendation-statement/bacterial-vaginosis-in-pregnant-adolescents-and-women-to-prevent-preterm-delivery-screening

USPSTF Program Office   5600 Fishers Lane, Mail Stop 06E53A, Rockville, MD 20857