Original Article

Ann Lab Med 2012; 32(3): 194-200

Published online May 1, 2012

Copyright © Korean Society for Laboratory Medicine.

The Prevalence of Vaginal Microorganisms in Pregnant Women with Preterm Labor and Preterm Birth

Seong Jin Choi, M.D.1, Soon Deok Park, M.S.2, In Ho Jang, M.S.2, Young Uh, M.D.2, and Anna Lee, M.D.3

Departments of Obstetrics & Gynecology1 and Laboratory Medicine2, Yonsei University Wonju College of Medicine, Wonju; Laboratory Medicine3, Seoul Medical Science Institute, Seoul, Korea

Correspondence to: Young Uh
Department of Laboratory Medicine, Yonsei University Wonju College of Medicine, 162 Ilsan-dong, Wonju 220-701, Korea
Tel: +82-33-741-1592
Fax: +82-33-731-0506

Received: October 17, 2011; Revised: December 11, 2011; Accepted: February 8, 2012

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background: To investigate the risk factors for vaginal infections and antimicrobial susceptibilities
of vaginal microorganisms among women who experienced preterm birth (PTB),
we compared the prevalence of vaginal microorganisms between women who experienced
preterm labor (PTL) without preterm delivery and spontaneous PTB.
Methods: Vaginal swab specimens from 126 pregnant women who experienced PTL were
tested for group B streptococcus (GBS), Mycoplasma hominis, Mycoplasma genitalium,
Ureaplasma urealyticum, Chlamydia trachomatis, Trichomonas vaginalis, Neisseria gonorrhoeae,
Treponema pallidum, herpes simplex virus (HSV) I and II, and bacterial vaginosis.
A control group of 91 pregnant women was tested for GBS. Antimicrobial susceptibility
tests were performed for GBS, M. hominis, and U. urealyticum.
Results: The overall detection rates for each microorganism were: U. urealyticum, 62.7%;
M. hominis, 12.7%; GBS, 7.9%; C. trachomatis, 2.4%; and HSV type II, 0.8%. The colonization
rate of GBS in control group was 17.6%. The prevalence of GBS, M. hominis, and
U. urealyticum in PTL without preterm delivery and spontaneous PTB were 3.8% and
8.7% (relative risk [RR], 2.26), 3.8% and 17.3% (RR, 4.52), and 53.8% and 60.9% (RR,
1.13), respectively, showing no significant difference between the 2 groups. The detection
rate of M. hominis by PCR was higher than that by culture method (11.1% vs. 4.0%, P =
0.010). The detection rates of U. urealyticum by PCR and culture method were 16.7% and
57.1%, respectively.
Conclusions: There was no significant difference in the prevalence of GBS, M. hominis, and
U. urealyticum between the spontaneous PTB and PTL without preterm delivery groups.

Keywords: Preterm labor, Preterm birth, Group B streptococcus, Mycoplasma hominis, Ureaplasma urealyticum