{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T06:49:57Z","timestamp":1776840597091,"version":"3.51.2"},"reference-count":32,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T00:00:00Z","timestamp":1776816000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>Whether bacteria exist in the pregnancy uterus without pathological infection has long been a controversial topic. Through this study, we aim to determine whether characteristic amniotic fluid microbiota exists in the uterus of high-risk pregnant women during the second trimester.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>This study recruited high-risk pregnant women in the second trimester from September 1, 2024, to August 30, 2025, and recorded their age and gestational age. Amniotic fluid samples were obtained through amniocentesis under strictly sterile conditions, and 16S rRNA high-throughput sequencing was performed on the samples. The inclusion criteria mainly consisted of: advanced maternal age, non-invasive prenatal test results indicating chromosomal abnormalities, abnormal fetal ultrasound findings, history of adverse pregnancy outcomes, and high-risk Down syndrome screening results.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      This study included a total of 50 high-risk pregnant women who underwent amniocentesis. The results showed that bacteria were present in all amniotic fluid samples, primarily composed of\n                      <jats:italic>Actinobacteriota<\/jats:italic>\n                      and\n                      <jats:italic>Proteobacteria<\/jats:italic>\n                      . There was no difference in amniotic fluid microbiota diversity between pregnant women under 35 years old and those 35 years or older; however, the abundances of\n                      <jats:italic>Cutibacterium<\/jats:italic>\n                      and\n                      <jats:italic>Leifsonia<\/jats:italic>\n                      differed between the two groups. A slight difference in microbiota diversity was observed between women with gestational ages below 20 weeks and those at 20 weeks or above, but no significant difference was found in microbial composition between the two groups.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>\n                      There was bacterial DNA in amniotic fluid of high-risk pregnant women in the second trimester, with\n                      <jats:italic>Actinobacteriota<\/jats:italic>\n                      and\n                      <jats:italic>Proteobacteria<\/jats:italic>\n                      being the predominant phyla, showing limited correlation with maternal age or gestational age. This study provided evidence for the presence of microorganisms in amniotic fluid during pregnancy and might offer some preliminary data for future research related to eugenics and reproductive health.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fcimb.2026.1748232","type":"journal-article","created":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T05:51:05Z","timestamp":1776837065000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["A primary study: high-throughput sequencing analysis of amniotic fluid microbiota in 50 high-risk pregnant women during the second trimester"],"prefix":"10.3389","volume":"16","author":[{"given":"Junhua","family":"Wu","sequence":"first","affiliation":[{"name":"Department of Pediatrics, The affiliated Women and Children\u2019s Hospital of Ningbo University","place":["Ningbo, Zhejiang, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yanbo","family":"Lu","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, The affiliated Women and Children\u2019s Hospital of Ningbo University","place":["Ningbo, Zhejiang, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhouyong","family":"Zheng","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, The affiliated Women and Children\u2019s Hospital of Ningbo University","place":["Ningbo, Zhejiang, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jishan","family":"Zheng","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, The affiliated Women and Children\u2019s Hospital of Ningbo University","place":["Ningbo, Zhejiang, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qiang","family":"Fu","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, Jingzhou Hospital Affiliated to Yangtze University","place":["Jingzhou, Hubei, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2026,4,22]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.7759\/cureus.17994","article-title":"Leifsonia species bacteremia in a hemodialysis patient: a difficult-to-identify organism","volume":"13","author":"Al-Sardi","year":"2021","journal-title":"Cureus"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1530\/rep-23-0078","article-title":"The dogma of the sterile uterus revisited: does microbial seeding occur during fetal life in humans and animals","volume":"167","author":"Banchi","year":"2023","journal-title":"Reproduction"},{"key":"B3","doi-asserted-by":"publisher","first-page":"235","DOI":"10.2217\/fmb-2022-0191","article-title":"Cutibacterium acnes (formerly Propionibacterium acnes): friend or foe","volume":"18","author":"Boyanova","year":"2023","journal-title":"Future Microbiol."},{"key":"B4","doi-asserted-by":"publisher","first-page":"801","DOI":"10.2217\/fmb-2020-0243","article-title":"Evidence of bacterial DNA presence in chorionic villi and amniotic fluid in the first and second trimester of pregnancy","volume":"16","author":"Campisciano","year":"2021","journal-title":"Future Microbiol."},{"key":"B5","doi-asserted-by":"publisher","first-page":"248","DOI":"10.4014\/jmb.1908.08016","article-title":"Vaginal microbiota profiles of native Korean women and associations with high-risk pregnancy","volume":"30","author":"Chang","year":"2020","journal-title":"J. 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