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Vaginal Microbiota in Short Cervix Pregnancy: Secondary Analysis of Pessary vs. Progesterone Trial
Antonio G Amorim Filho1, Roberta C R Martins2, Lucas A M Franco2
1Disciplina de Obstetricia, Departamento de Obstetricia e Ginecologia, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo 05403-000, Brazil.
Insights
Vaginal progesterone and Arabin pessary interventions did not alter the vaginal microbiome in women at high risk for preterm birth (PTB). Both treatments demonstrated microbiological safety for PTB prevention strategies.
Area of Science:
- Reproductive Medicine
- Microbiome Research
- Obstetrics
Background:
- Preterm birth (PTB) is a major cause of neonatal mortality, especially in women with short cervixes.
- Vaginal dysbiosis is linked to increased PTB risk.
- The impact of progesterone (PR) and Arabin pessary (PE) on the vaginal microbiome for PTB prevention is not well understood.
Purpose of the Study:
- To compare the effects of vaginal progesterone and Arabin pessary on vaginal microbiome composition in women at high risk for PTB.
- To assess the microbiological safety of these interventions.
Main Methods:
- Secondary analysis of a randomized trial involving 203 pregnant women with cervical length ≤ 25 mm.
- 44 participants were assigned to daily vaginal progesterone (200 mg) or an Arabin pessary.
- Vaginal swabs analyzed using 16S rRNA gene sequencing at baseline and 4 weeks post-treatment.
Main Results:
- Most participants (80/88) exhibited a low-diversity, Lactobacillus-dominated microbiota (CST-III or CST-I/II/V).
- No significant changes in community state types (CST), Shannon alpha diversity, or Bray-Curtis dissimilarity were observed in either the progesterone or pessary group after treatment.
- Both interventions maintained the stability of the vaginal microbiome.
Conclusions:
- Arabin pessary and vaginal progesterone treatments maintain vaginal microbiome stability in high-risk PTB populations.
- These findings support the microbiological safety of both interventions for PTB prevention.
Background/Objectives:
Preterm birth (PTB) is a leading cause of neonatal mortality, particularly in women with a short cervix. Vaginal dysbiosis has been associated with increased PTB risk. Progesterone (PR) and Arabin pessary (PE) are commonly used for PTB prevention, but their impact on vaginal microbiome composition is unclear. This study aimed to compare the effects of these interventions on the vaginal microbiome in women at risk of PTB.
Methods:
In a secondary analysis of a randomized trial at Hospital das Clínicas, Universidade de São Paulo, 203 women with singleton pregnancies and cervical length ≤ 25 mm at the second trimester were assigned to daily vaginal PR (200 mg) or PE. Vaginal swabs from 44 participants (n = 22 per group) were collected at baseline and 4 weeks post-treatment and analyzed via 16S rRNA gene sequencing.
Results:
From 88 samples analyzed, 80 showed a low-diversity, Lactobacillus-dominated microbiota, 42 classified into Lactobacillus iners-dominated community state type (CST-III), and 38 presented other Lactobacillus species dominance (termed CST-I/II/V). The remaining eight samples presented non-Lactobacillus dominance (CST-IV). Comparing the two groups, no significant changes in CST were observed between sampling timepoints (PE group, p = 0.368; PR group, p = 0.223). Similarly, Shannon alpha diversity did not change (PE group, p = 0.62; PR group, p = 0.30), and Bray-Curtis dissimilarity also did not change after treatment (p = 0.96, before; p = 0.87, after treatment).
Conclusions:
Arabin pessary and vaginal progesterone maintain vaginal microbiome stability in women at high PTB risk, supporting the microbiological safety of both interventions.
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