Aetiology of preterm labour: bacterial vaginosis

Abstract

Bacterial vaginosis (BV) is a common condition characterised by a polymicrobial disorder, with an overgrowth of several anaerobic or facultative bacteria and with a reduction or absence of lactobacillus colonisation. The prevalence of BV ranges from 4 to 64%, depending on the racial, geographic and clinical characteristics of the study population. In asymptomatic women, the prevalence varies from 12 to 25%, and similar percentages are observed in pregnant women. Although BV is associated with several adverse outcomes, such as upper genital tract infections, pelvic inflammatory disease, endometritis, preterm birth and low birthweight, many basic questions regarding the pathogenesis of BV remain unanswered. Mucosal immune system activation may represent a critical determinant of adverse consequences associated with BV. An unequal risk for BV acquisition and\or recurrence could derive from different mucosal immune host abilities and\or capability of invading microbes to produce factors that inactivate the local immune response. BV is associated with a two-fold increased risk of preterm birth, with the greatest risk when BV is present before 16 weeks of gestation (odds ratio = 7.55). This may indicate a critical period during early gestation when BV-related organisms can gain access to the upper genital tract and set the stage for spontaneous preterm labour later in gestation. The results of treatment trials for pregnant women with BV have been heterogeneous, with anywhere from an 80% reduction to a two-fold increase in preterm birth among women who received treatment. For this reason, in current clinical practice significant controversy surrounds determining not only who and when to screen but also who and how to treat. Recent evidence shows that individual genetic backgrounds can affect chemokine production. This is an interesting area for future research and could lead to trials of treatment only for women genetically predisposed to preterm birth.

Prevalence of bacterial vaginosis in preterm and term labour: a one year study

“…3 The pathogenesis of Bacterial vaginosis during pregnancy is associated with many complications like chorioamnionitis, preterm birth and low birth weight among neonates. 4 The greatest risk of preterm birth is observed if Bacterial vaginosis is present before 16 weeks of gestation.…”

Normal flora and bacterial vaginosis in pregnancy: an overview

“…The first 16 weeks of pregnancy possibly marks a critical stage during which BV enters the upper genital tract because women in this gestation period are at highest risk for PTB (Guaschino et al, 2006). The reason why some women with BV are more prone to deliver preterm can in part be explained by genotype-environment interactions (Denney and Culhane, 2009).…”

“…Bacterial vaginosis has also been linked with other complications, including intrauterine infection, chorioamnionitis and postoperative abortive infections (Kurki et al, 1993;Govender et al, 1996;Guaschino et al, 2006). Women with pelvic inflammatory disease (PID) are more commonly affected by BV but this disease entity alone does not result in pruritus, dysuria, burning or any inflammation in the vagina (Klebanoff et al, 2004;Sobel et al, 2012).…”

Study of prevalence of bacterial vaginosis in preterm and term labour

“…4 Spontaneous preterm labor is mostly found approximately 30-50% and bacterial vaginosis is one of the many causes of preterm labor. Pregnancy with bacterial vaginosis is a higher risk for preterm delivery.…”