Oral, Vaginal, and Placental Microbiota Profiles in Japanese Pregnancies with Preterm Birth and Chronic Abruption-Oligohydramnios Sequence (CAOS): A Cross-Sectional Study

Yuka Fukuma ¹, Yoshifumi Kasuga ¹, Keisuke Akita ¹

⁰Department of Obstetrics and Gynecology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.

Medicina (Kaunas, Lithuania) +

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December 31, 2025

View abstract on PubMed

Summary

Investigating the oral, vaginal, and placental microbiota in pregnant women revealed significant differences in placental microbial composition, particularly with Ureaplasma species, in preterm birth (PTB) cases. This suggests a potential microbial role in PTB pathogenesis.

Area Of Science

Microbiology
Obstetrics
Genomics

Background

Preterm birth (PTB) presents significant medical and economic challenges in perinatal care.
16S rRNA gene sequencing advances enable detailed microbiota analysis, crucial for understanding PTB pathogenesis.
Investigating microbial profiles in oral, vaginal, and placental sites may illuminate PTB causes.

Purpose Of The Study

To analyze oral, vaginal, and placental microbiota profiles in Japanese women hospitalized for preterm labor.
To examine associations between these microbiota and perinatal outcomes.
To explore the role of specific microbes, like Ureaplasma, in PTB.

Main Methods

Cross-sectional study of 20 pregnant Japanese women with preterm labor.
Collection of oral, vaginal, and placental samples.
16S rRNA gene sequencing for microbiota analysis and statistical group comparisons.

Main Results

No significant differences in oral or vaginal microbiota diversity across term birth, CAOS, and PTB groups.
A trend towards altered vaginal microbial composition in CAOS and PTB groups.
Significant differences in placental microbiota beta diversity among the groups, with increased Ureaplasma urealyticum in PTB and Ureaplasma parvum in CAOS.

Conclusions

Placental microbiota alterations are associated with preterm birth (PTB) and chronic abruption-oligohydramnios sequence (CAOS).
Specific Ureaplasma species abundance differs between PTB and CAOS groups.
Findings suggest a potential microbial contribution to PTB and related conditions.

Keywords:

16S rRNA gene sequencing chronic abruption-oligohydramnios sequence microbiota preterm birth vaginal dysbiosis