Background:In the last two decades the incidence of sexually transmitted infections (STIs) are dramatically increased and remain a major public health problem in developing countries. Trichomoniasis is the most common non-viral sexually transmitted infection caused by Trichomonas vaginalis which is a flagellated protozoon associated with vaginitis, cervicitis and urethritis. Researchers believed that pregnancy is one of the influencing factors of the genital trichomoniasis in women. Objectives: The aim of this study was to determine the prevalence of trichomoniasis in pregnant women in Zanjan, Iran. Materials and Methods:In this cross-sectional study, 1000 pregnant women were examined for diagnosis of trichomoniasis based on direct microscopic examination and culture method. They referred to the treatment and health centers of Zanjan, Northwest Iran, Demographic and personal information of the subjects were collected and evaluated with questionnaires. Results: Thirty-three out of one thousand examined individuals (3.3%) presented vaginal infection with T. vaginalis. Infection in women with lower gestational age, higher mothers' age, higher parity and living in city were significantly associated with increased risk of vaginal trichomoniasis (P < 0.05). Other variables were not significantly associated with parasite infection. Conclusions: The present study found that the infection with T. vaginalis is a health problem in pregnant women correlated with some epidemiological variables and can be considered with microbiological screening tests during pregnancy.

Background: Available information suggests that pregnant women infected with Trichomonas vaginalis may be at increased risk of preterm delivery and low birth weight (LBW). This study evaluated the association between T. vaginalis infection and the risk of LBW.Methods: In this cohort study, we evaluated 1000 pregnant women (gestational age ≥ 28weeks) for trichomoniasis by using direct and culture methods at the time of delivery at two hospitals of Zanjan, Iran. All the infected women (33 cases) and non-infected women (107) who had been selected with purposive quota sampling were compared with each other. Questionnaires were used to collect demographic and obstetric parameters. Consequently, infants' weights were recorded using mothers' files.Results: The prevalence of T. vaginalis infection was 3.3% (33 cases). Mean gestational age of the infected women at the time of delivery was significantly less than the non-infected (36.5 ± 4.5 weeks vs. 39 ± 1.9 weeks; P= 0.009). Higher parity, and living in city were significantly associated with the increased risk of vaginal trichomoniasis (P< 0.05). No significant association was found between the T. vaginalis infection and degree of education, type of delivery, family income, and frequency of LBW. Conclusion:The results of this study suggest that, T. vaginalis infection may be associated with lowgestational age and higher parity at the time of delivery. However, no significant association was found between the T. vaginalis infection and LBW in the third trimester of pregnancy.