LAUSR

To clarify the risk factors for chlamydial infection and determine whether infection during pregnancy is associated with preterm birth in Japanese women. The subjects were women who underwent Chlamydia trachomatis polymerase chain reaction testing during a singleton pregnancy and delivered after the 22nd week of gestation at a tertiary care center between January 1, 2000 and December 31, 2016. We compared Chlamydia-positive (n=259) and Chlamydia-negative (n=1,974) groups and evaluated the pregnancy outcomes. The Chlamydia-positive group had a higher rate of public assistance coverage, smoking during pregnancy, nulliparity, lack of a partner, presence of other sexually transmitted infections, high-risk social status, and younger age (p<0.01). There was no difference between the groups in the incidence of preterm births, with an odds ratio of 0.95 (95% confidence interval: 0.62-1.46); the incidence of low birth weight deliveries, premature rupture of membranes, and preterm premature rupture of membranes prior to the 37th week were also comparable between the groups. Chlamydial infection during pregnancy had no effect on preterm birth, even after adjustment for confounding factors.