Ureaplasma urealyticum and chronic lung disease of prematurity: critical appraisal of the literature on causation.

A critical appraisal of four cohort studies examining the relationship between Ureaplasma urealyticum and chronic lung disease (CLD) of prematurity is presented. Three studies were concurrently conducted, but the fourth was conducted 4 years later when surfactant replacement was a widespread practice. Although infants were enrolled in all studies soon after birth before they had developed CLD, there were differences in patient population, the definition of colonization with U. urealyticum, neonatal management, and the definition of CLD of prematurity. Despite the differences, all four studies found an association between colonization and development of CLD of prematurity