Managing Sexually Transmitted Infections in Pregnant Women

Nadi K Gupta; Christine A Bowman


Women's Health. 2012;8(3):313-321. 

In This Article


Bacterial Vaginosis

Bacterial vaginosis is not regarded as an STI but its prevalence is higher in sexually active women. Bacterial vaginosis is a condition resulting from replacement of the usual H2O2 lactobacilli in the vagina with anaerobic bacteria such as Mobiluncus sp. and Gardnerella vaginalis. It is a common cause of vaginal discharge in women of childbearing age but 50% of patients may be asymptomatic. A prevalence rate of 12% was found in pregnant women attending an antenatal clinic in the UK.[38] The pathophysiology, particularly in the context of pregnancy, is poorly understood.[39] Bacterial vaginosis is associated with increased risk of preterm delivery, postpartum endometritis and pelvic inflammatory disease.[40]

The diagnosis can be confirmed using either clinical (Amsel's) criteria or Gram stain (Nugent or Hay-Ison) criteria. Amsel's criteria require at least three out of four of the following to be present: thin, white homogeneous discharge, clue cells on microscopy of wet mount, pH of vaginal fluid >4.5 or release of fishy odor upon adding alkali (10% potassium hydroxide).[41] This so-called amine or 'whiff' test is not often performed in genitourinary medicine clinics now for health and safety reasons.

The Nugent score is determined by estimating the relative concentration of bacterial morphotypes that occur in bacterial vaginosis.[42] UK guidelines recommend using the Hay-Ison criteria:

  • Grade 1/normal: Lactobacillus morphotypes predominate;

  • Grade 2/intermediate: mixed flora with some lactobacilli present, but Gardnerella or Mobiluncus morphotypes also present;

  • Grade 3/bacterial vaginosis: predominantly Gardnerella and/or Mobiluncus with few or absent lactobacilli.[43]

Treatment of Bacterial Vaginosis in Pregnancy Symptomatic women should be treated. However, the same as in nonpregnant women, asymptomatic pregnant women may opt for treatment if offered.

There are conflicting data regarding the value of screening and treating bacterial vaginosis in pregnancy. Evidence from systematic reviews does not support the routine screening and treatment of pregnant women with bacterial vaginosis.[44] However, other data suggest that screening and treating women at high risk for preterm delivery based on their history may significantly reduce the risk for preterm delivery.[45–47]

Metronidazole is the drug of choice and has an estimated cure rate of at least 70%.[48] Alcohol should be avoided during treatment and for 48 h after to prevent a disulfiram-like reaction.

Recommended regime for bacterial vaginosis in pregnancy can be found in Box 6 .

Routine screening and treatment of male sexual partners is not required as studies have not shown any effect on likelihood of relapse.[49]


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