Plain language summary Antenatal screening for HIV, syphilis and HBV has been successfully implemented in The Netherlands, but data on other STI among pregnant women or male partners are limited. Our objectives were: (i) to assess the prevalence of Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and Trichomonas vaginalis (TV) among pregnant women and male partners, (ii) to identify risk factors for these STI during pregnancy, and (iii) to identify adverse perinatal outcomes (APO) associated with STI. Pregnant women aged = 2 sex partners < 12 months. APO was not associated with STI, but was associated with female low education, complications with previous newborn, and short duration of the relationship. Small-for-gestational-age was not associated with STI, but was associated with female low education, female non-Western background, and both parents smoking during pregnancy. Prevalence of STI was low among pregnant women and male partners in midwifery practices, except for CT among young women. The study could not confirm previously observed associations between STI and APO. Probably due to low prevalence of STI, small study sample, and presumed treatment for STI. Background Antenatal screening for HIV, syphilis and HBV has been successfully implemented in The Netherlands, but data on other STI among pregnant women or male partners are limited. Our objectives: (i) to assess the prevalence of Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and Trichomonas vaginalis (TV) among pregnant women and male partners, (ii) to identify risk factors for these STI during pregnancy, and (iii) to identify adverse perinatal outcomes (APO) associated with STI. Methods Cross-sectional study. Pregnant women aged = 21 years) (adjusted OR 6.52, CI 95%: 1.11-38.33), male non-Western vs Western background (aOR 9.34, CI 2.34-37.21), and female with >= 2 sex partners < 12 months vs 0-1 (aOR 9.88, CI 2.08-46.91). APO was not associated with STI, but was associated with female low education (aOR 3.36, CI 1.12-10.09), ...