The Associations of Genital Mycoplasmas with Female Infertility and Adverse Pregnancy Outcomes: a Systematic Review and Meta-analysis

The roles of genital mycoplasmas including Mycoplasma genitalium (M. genitalium), Mycoplasma hominis (M. hominis), Ureaplasma urealyticum (U. urealyticum), and Ureaplasma parvum (U. parvum) in reproductive diseases are equivocal. To investigate whether genital mycoplasmas are risk factors of female infertility and adverse pregnancy outcomes, we performed a systematic review and meta-analysis. Electronic databases were searched for related studies. A random-effects model or fixed-effects model was employed to generate forest plots. Pooled odd ratios (ORs) with 95% confidence intervals (CIs) were applied to measure the strength of associations. Meanwhile, heterogeneity was evaluated by H statistic and I-2 statistic, and publication bias was explored by funnel plots based on Egger's test and Begg's test. The search yielded 2054 relevant records, and 35 articles were ultimately included for meta-analysis. M. genitalium was a significant risk factor for female infertility (OR, 13.03 [95% CI, 3.46-48.98]) and preterm birth (PTB) (OR, 1.81 [95% CI, 1.17-2.80]), but not for spontaneous abortion (SA) (OR, 0.58 [95% CI, 0.25-1.35]). M. hominis can significantly increase the potential risk of female infertility (OR, 1.56 [95% CI, 1.02-2.38]), SA (OR, 9.14 [95% CI, 4.14-20.18]), stillbirth (OR, 3.98 [95% CI, 1.39-11.36]), and premature rupture of membranes (PROM) (OR, 1.79 [95% CI, 1.26-2.55]), but was not associated with PTB (OR, 1.29 [95% CI, 0.78-2.15]). U. urealyticum had no significant risk effect on female infertility (OR, 0.68 [95% CI, 0.42-1.11]). Coinfections of M. hominis and Ureaplasma were significantly associated with female infertility, SA, and stillbirth, but not with PROM. On the basis of current evidences, this meta-analysis supports that M. genitalium is a risk factor for female infertility and PTB; M. hominis is a potential risk factor for female infertility, SA, stillbirth, and PROM; U. urealyticum has no significant association with female infertility; and the relationship of U. parvum with female infertility and adverse pregnancy outcomes needs to be paid more attention to and remains to be further revealed.