Antibiotics for treating bacterial vaginosis in pregnancy

 

Abstract

Background

Bacterial vaginosis is an imbalance of the normal vaginal flora with an overgrowth of anaerobic bacteria and a lack of the normal lactobacillary flora. Bacterial vaginosis during pregnancy has been associated with poor perinatal outcome and, in particular, preterm birth (PTB). Identification and treatment may reduce the risk of PTB and its consequences.

Objectives

To assess the effects of antibiotic treatment of bacterial vaginosis in pregnancy.

Search strategy

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2006). We updated this search on 18 November 2010 and added the results to the awaiting classification section.

Selection criteria

Randomized trials comparing antibiotic treatment with placebo or no treatment, or comparing two or more antibiotic regimens in pregnant women with bacterial vaginosis or intermediate vaginal flora.

Data collection and analysis

Two review authors assessed trials and extracted data independently. We contacted study authors for additional information.

Main results

We included fifteen trials of good quality, involving 5888 women. Antibiotic therapy was effective at eradicating bacterial vaginosis during pregnancy (Peto odds ratio (OR) 0.17, 95% confidence interval (CI) 0.15 to 0.20; 10 trials, 4357 women). Treatment did not reduce the risk of PTB before 37 weeks (Peto OR 0.91, 95% CI 0.78 to 1.06; 15 trials, 5888 women), or the risk of preterm prelabour rupture of membranes (PPROM) (Peto OR 0.88, 95% CI 0.61 to 1.28; four trials, 2579 women). However, treatment before 20 weeks' gestation may reduce the risk of preterm birth less than 37 weeks (Peto OR 0.72, 95% CI 0.55 to 0.95; five trials, 2387 women). In women with a previous PTB, treatment did not affect the risk of subsequent PTB (Peto OR 0.83, 95% CI 0.59 to 1.17, five trials of 622); however, it may decrease the risk of PPROM (Peto OR 0.14, 95% CI 0.05 to 0.38) and low birthweight (Peto OR 0.31, 95% CI 0.13 to 0.75)(two trials, 114 women). In women with abnormal vaginal flora (intermediate flora or bacterial vaginosis) treatment may reduce the risk of PTB before 37 weeks (Peto OR 0.51, 95% CI 0.32 to 0.81; two trials, 894 women). Clindamycin did not reduce the risk of PTB before 37 weeks (Peto OR 0.80, 95% CI 0.60 to 1.05; six trials, 2406 women).

Authors' conclusions

Antibiotic treatment can eradicate bacterial vaginosis in pregnancy. This review provides little evidence that screening and treating all pregnant women with asymptomatic bacterial vaginosis will prevent PTB and its consequences. However, there is some suggestion that treatment before 20 weeks' gestation may reduce the risk of PTB. This needs to be further verified by future trials.

[Note: The eleven citations in the awaiting assessment section of the review may alter the conclusions of the review once assessed.]

 

Plain language summary

Antibiotics for treating bacterial vaginosis in pregnancy

Antibiotics during pregnancy for overgrowth of abnormal bacteria in the birth canal does not reduce the risk of babies being born too early.

Bacteria are normally present in the birth canal and are useful in maintaining the health of the vagina. However, if the numbers of abnormal bacteria increase, this may cause an unpleasant discharge and may cause some babies to be born too early. The review of 15 trials, involving 5888 women, found that antibiotics given to pregnant women reduced this overgrowth of bacteria, but did not reduce the numbers of babies who were born too early. The effect of earlier treatment needs to be studied in further trials.