Is genital colonization with Mycoplasma hominis or Ureaplasma urealyticum associated with prematurity/low birth weight?

Mycoplasma species have been implicated in the pathogenesis of prematurity, intrauterine growth retardation, low birth weight (LBW), and preterm premature rupture of membranes. The purpose of this study was to review the available literature to determine whether there is an association between genital colonization with Mycoplasma hominis or Ureaplasma urealyticum and prematurity/LBW. Twelve studies were reviewed: nine cohort studies, two case-control studies, and one randomized clinical trial of treatment. The overall isolation rate of M hominis from the genital tract was 27.2%, whereas that of U urealyticum was 70.4% (cohort studies). Results from the randomized clinical trial showed that treatment did not alter the rate of prematurity in women carrying mycoplasma species in the genital tract. None of the cohort studies supported an association between genital colonization with U urealyticum and prematurity/LBW. Similarly, no association between M hominis and prematurity/LBW could be demonstrated in seven of the eight and in six of the eight cohort studies, respectively. On the other hand, two case-control studies showed an association between U urealyticum colonization and prematurity without an association with M hominis. We conclude that the weight of the evidence does not support an association between genital colonization with mycoplasma species and prematurity/LBW.