This study investigated the prevalence of Chlamydia trachomatis, Ureaplasma urealyticum and Mycoplasma hominis infections in the cervices and peritoneum of pregnant women and compared them with non-pregnant controls. A total of 96 pregnant women who planned to deliver by caesarean section, and 124 non-pregnant women were screened for cervical Chlamydia trachomatis, Ureaplasma urealyticum and Mycoplasma hominis infections by polymerase chain reaction analysis. If cervical infection was present, peritoneal infection was searched from the Pouch of Douglas during caesarean section in the pregnant group and was searched by culdocentesis in the control group. Chlamydia trachomatis infection was present in 7.3% of pregnant women and 2.4% of the non-pregnant controls. Ureaplasma urealyticum infection was present in 26% of pregnant women and 15.3% of the non-pregnant controls. The incidence of Chlamydia trachomatis and Ureaplasma urealyticum infection was significantly higher in pregnancy. Mycoplasma hominis infection was present less frequently compared with Chlamydia trachomatis and Ureaplasma urealyticum in both groups. Intraperitoneal colonisation by Chlamydia trachomatis was present in only one pregnant woman and in one non-pregnant control. No intraperitoneal infection was detected for Ureaplasma urealyticum and Mycoplasma hominis. Cervical Ureaplasma urealyticum and Chlamydia trachomatis infections were more frequently seen in pregnant Turkish women.