General Obstetrics and Gynecology Obstetrics
Bacterial vaginosis as a risk factor for preterm delivery: A meta-analysis

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Abstract

Objective: We performed a meta-analysis to evaluate bacterial vaginosis as a risk factor for preterm delivery. Study Design: Selection criteria were (1) the data appeared in original, published English-language reports of prospective studies or control groups of clinical trials that included women at <37 weeks of gestation with intact amniotic membranes, (2) all the women had to have been screened for bacterial vaginosis that was diagnosed by either clinical criteria or criteria that were based on Gram stain findings, and (3) the outcomes were preterm delivery, spontaneous abortion, maternal or neonatal infection, and perinatal death. Results: Eighteen studies with results for 20,232 patients were included. Bacterial vaginosis increased the risk of preterm delivery >2-fold (odds ratio, 2.19; 95% CI, 1.54-3.12). Higher risks were calculated for subgroups of studies that screened for bacterial vaginosis at <16 weeks of gestation (odds ratio, 7.55; 95% CI, 1.80-31.65) or at <20 weeks of gestation (odds ratio, 4.20; 95% CI, 2.11-8.39). Bacterial vaginosis also significantly increased the risk of spontaneous abortion (odds ratio, 9.91; 95% CI, 1.99-49.34) and maternal infection (odds ratio, 2.53; 95% CI, 1.26-5.08). No significant results were calculated for the outcome of neonatal infection or perinatal death. Conclusion: Bacterial vaginosis, early in pregnancy, is a strong risk factor for preterm delivery and spontaneous abortion. (Am J Obstet Gynecol 2003;189:139-47.)

Section snippets

Material and methods

In July 2001, we searched MEDLINE entries from 1966 to the present, EMBASE from 1988 to the present, and SCIENCE CITATION INDEX EXPANDED from 1997 to the present to identify all literature that was included (vaginitis or vaginosis or vagina* infection or vagina* inflammation or “Vaginosis-Bacterial”/ explode or “Vaginitis”/explode) and (pregnan* or gravid* or birth? or labo?r? or “Pregnancy”/explode or “Labor”/explode). The following criteria were used to select studies for inclusion: article

Results

A total of 18 studies with results for 20,232 patients were included.3, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26 For 1 of the studies, the “Preterm Prediction Study” (a large study that was carried out by the National Institute of Child Health and Human Development), numerous reports were published. Three of these studies were used to extract results for the outcomes of delivery at <37 weeks of gestation,3 <35 weeks of gestation,23 or <32 weeks of gestation3 and

Comment

The results of this meta-analysis confirm that BV is associated significantly with adverse pregnancy outcome and that the risk of preterm delivery at <37 weeks of gestation, as calculated in the main analysis, is >2-fold in women with BV. The considerable and highly significant statistical heterogeneity that was seen in this main analysis, however, makes it clear that this combined result is only a crude estimate of the strength of the association between BV and preterm birth, but it has no

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    Reprint requests: Harald Leitich, MD, PhD, Department of Obstetrics and Gynecology, University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria. E-mail: [email protected]

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