Relationship between Vaginal Bacterial Infections and Pregnancy Outcomes: A Systematic Review and Meta Analysis

Hojjat Rokni, Amjad Ahmadi, Yousef Moradi, Bijan Nouri, Daem Roshani


Background: Bacterial infections are among the most serious infections worldwide. They can cause miscarriage, premature birth, stillbirth, and ectopic pregnancy in pregnant women. The aim of this study was to investigate the relationship between bacterial infections and pregnancy outcomes through a systematic review and meta‑analysis.

Materials and Methods: PubMed, Scopus, Web of Science, and Embase databases were searched from January 2000 to December 2018 using appropriate keywords to identify related articles. The final related studies were selected and evaluated using the Newcastle‑Ottawa Scale (NOS).

Results: Results of this meta‑analysis based on combining case‑control studies showed that the presence of bacterial infections could lead increase in the odds of all pregnancy outcomes like premature infant birth (odd ratio [OR]: 1.50; 95% Confidence Interval [CI], 1.39–1.61), preterm delivery (OR: 1.54; 95% CI, 1.39–1.70), abortion (OR: 1.16; 95% CI, 1.04–1.29), stillbirth (OR, 1.29; 95% CI, 1.12–1.49), and ectopic pregnancy (OR: 1.12; 95% CI, 1.05–‑1.19). The results showed that the Risk Ratio (RR) of preterm delivery in pregnant women with vaginal infections was 1.57 (95% CI, 1.46–1.67), whereas the RR of abortion was 2.02 (95% CI, 1.72–2.38).

Conclusions: Based on the results of this meta‑analysis, the presence of bacterial infections in pregnant women can lead increase in the risk of pregnancy outcomes especially, preterm delivery, abortion, stillbirth, and ectopic pregnancy. Therefore, it is necessary for obstetricians and gynecologists to pay attention to the diagnosis of these infections in women before pregnancy and during pregnancy in order to prevent the consequences of these infections.


Abortion, bacterial infections, ectopic pregnancy, premature births, stillbirths

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