High-density vaginal Ureaplasma urealyticum colonization as a risk factor for chorioamnionitis and preterm delivery

background The aim of this case control study was to investigate the influence of genital Ureaplasma urealyticum colonization on pregnancy outcome. Methods. One hundred and seventy-two women colonized with Ureaplasma urealyticum without co-existing other infections and 123 women with negative cultures for Ureaplasma urealyticum were enrolled. In a multivariate analysis the influence of quantitative Ureaplasma urealyticum colonization level was determined. Results. Compared to the negative women increasing colonization with Ureaplasma urealyticum was associated with a significant decrease of birth weight (p < 0.0001) and gestational age (p < 0.0001) and with a significant increase of chorioamnionitis (p < 0.0001) and preterm delivery (p < 0.001). In a multivariate analysis high-density Ureaplasma urealyticum colonization was an independent risk factor for chorioamnionitis and preterm delivery, whereas low colonization levels had no effect on an adverse outcome of pregnancy. Conclusions. The degree of colonization with Ureaplasma urealyticum correlates strongly with an adverse effect on pregnancy outcome.