Effect of the Arabin pessary and natural progesterone on the vaginal microbiome

Abstract

Abstract Background Preterm birth is a leading cause of infant morbidity and mortality. Regardless of its multifactorial nature, it has been demonstrated that vaginal infections, as well instability of the local microbiome, can play a role as risk factors. The aim of the present study was to investigate possible changes in vaginal microbiome composition due to the use of an Arabin pessary or vaginal progesterone tablets in pregnant women as secondary prevention of preterm birth. Results We did a prospective analysis of 44 pregnant women at risk of preterm birth for a short cervix (≤ 25 mm) observed on transvaginal ultrasound in the second trimester and randomly assigned to receive an Arabin pessary (PE, n = 22) or vaginal progesterone (PR, n = 22). Vaginal swabs were collected upon diagnosis of short cervix and 4 weeks after treatment initiation to determine the Nugent score and microbiome profiles. The observed microbiomes could be assigned to 3 Community-State Types (CSTs) and most of the samples were characterized by a low-diversity, lactobacilli-dominated microbiota composition that remained stable after the onset of treatment. No treatment-associated change in microbiome alpha diversity was observed in either PE or PR and beta diversity analyses showed no significant dissimilarity between study groups or sampling times. Also, by an analysis of composition (ANCOM) no taxa with differential abundance were demonstrated. Conclusions Pessary and progesterone treatment for a short cervix appear to be equivalent regarding stability of the vaginal microbiome and thus patients and practitioners should be reassured about the safety of these methods.