European Journal of Obstetrics & Gynecology and Reproductive Biology
Full length articleChlamydia trachomatis screening in preterm labor: A systematic review and meta-analysis
Introduction
About ten percent of pregnancies in the United States are affected by preterm birth and subsequently increased infant morbidity and mortality [1]. Spontaneous preterm labor (PTL) is responsible for approximately half of all preterm births [2]. Research focused on exploring the etiology of preterm birth remains inconclusive, likely because of its multifactorial nature.
Intrauterine infection is an important risk factor for PTL [3]. Studies examining the colonization of the maternal genital tract by several specific organisms, such as gonorrhea, trichomonas and bacterial vaginosis, have consistently showed associations with preterm birth [4,5]. Chlamydia trachomatis is the most common bacterial sexually transmitted infection (STI) in the United States. In the US in 2016 there were more than 1.59 million infections reported to the Centers for Disease Control (CDC) [1]. Genital Chlamydia trachomatis infections in women are generally asymptomatic. In pregnant women, Chlamydia trachomatis infections have been associated with preterm prelabor rupture of membranes (PROM) and preterm birth, though the results are conflicting [6,7]. This has also been true of newer studies using sensitive DNA amplification techniques [8,9]. To date, studies have shown that treatment of Chlamydia trachomatis in pregnancy leads to a decrease in the incidence of PPROM and low birth-weight but its impact on PTL has not previously been specified [10,11].
The aim of this study was to evaluate the overall prevalence of Chlamydia trachomatis infections in pregnant women with threatened PTL compared to those who do not have threatened PTL through systematic review and meta-analysis.
Section snippets
Data sources
The review was designed a priori and followed the Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines for reporting of observational studies established for systematic reviews [12]. We searched Medline, ClinicalTrials.gov, Embase, Science direct, the Cochrane Library at the CENTRAL Register of Controlled Trials from establishment until May 2018. Search items used were combinations of: “Chlamydia”, “vaginal cervical infection” and “preterm labor”. Language or geographic
Ethical approval
Ethical committee and institutional review board approval was not required for this systematic review and meta-analysis.
General characteristics of the studies
Articles for 16 studies were assessed for eligibility and we identified four studies screening for Chlamydia trachomatis in women with threatened PTL (Fig. 1). Six studies examined women not in PTL. One study included women prior to 24 weeks gestation. Three studies had no controls. One study screened with serum antibodies. One study used a compromised method of sample collection with a thorough saline wash conducted prior to sample collection.
The characteristics of the four included studies
Comment
Chlamydia trachomatis infections during pregnancy have been associated with PROM and premature delivery [[6], [7], [8], [9]]. Treatment of Chlamydia trachomatis in pregnancy leads to a decrease in the incidence of preterm PROM and low birth-weight; however, its impact on symptoms of PTL remains unclear [10,11]. There have been no randomized trials to examine if universal or risk based screening in pregnancy improves outcomes. This is likely because the deleterious nature of this bacterium in
Strengths and limitations
The four studies included in this review are limited by a small number of patients and incompletely defined study and control groups (Table 1). In addition, screening techniques differed between studies with culture and NAAT techniques being utilized. Though specificity is similar between NAAT and cultures, sensitivity is largely accepted as greater with the NAAT technique [13]. Importantly, two of the studies provided data indicating that the study group had a higher rate of a history of
Conclusion
PTL is responsible for approximately half of all preterm births with intrauterine infection being an important risk factor for PTL. Chlamydia trachomatis infections have been associated with PROM and preterm birth, but its impact on PTL has not previously been specified. Four studies screening for Chlamydia trachomatis in women with threatened PTL were identified. The incidence of Chlamydia trachomatis in women with threatened PTL is approximately 9%, and significantly increased compared to
Funding
The authors received no funding for this manuscript.
Declaration of Competing Interest
The authors report no conflict of interest.
Acknowledgments
Lynn Stierle (Department of Obstetrics and Gynecology, Thomas Jefferson University), Hagay Gershi, MD (Department of Obstetrics and Gynecology, Mayanei Hayeshua Medical Center, Bnei Brak, Israel), Ilona Lalova (United Nations Children’s Fund) for their assistance with translations and with the literature search.
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