Ureaplasma urealyticum infection of the placenta in pregnancies that ended prematurely.

To investigate the relationship between Ureaplasma urealyticum infection of the placenta and premature onset of labor. We studied 647 pregnancies that resulted in the live birth of an infant weighing less than 1501 g. The chorionic surface of the placenta was cultured for U urealyticum, Mycoplasma hominis, and group B streptococci. The rate of ureaplasma isolation increased with increasing interval between rupture of membranes and delivery. When analyses were limited to the 96 singleton pregnancies that ended within 1 hour of rupture of membranes and before the 29th week of gestation, U urealyticum was prominently associated with an increased risk of premature onset of labor (P = .008 unadjusted, and P = .05 when adjustment was made for all potential confounders). Ureaplasma infection rate was lowest in pregnancies terminated because of severe maternal preeclampsia or progressive fetal growth restriction. Ureaplasma urealyticum infection is associated with premature onset of labor and with increasing duration of time between rupture of membranes and delivery. Eradication of ureaplasmas from the urogenital tract of women and their partners, ideally before conception, should be considered.