Jundishapur J Microbiol. 2020 March; 13(3):e92549. Published online 2020 April 12. doi: 10.5812/jjm.92549. Research Article Transmission Rates of Chlamydia trachomatis and Neisseria gonorrhoeae Infections from Pregnant Women to Newborns, Tehran, Iran Abdoulreza Esteghamati 1 , Ali Mazouri 2 , Shirin Sayyahfar 1 , Khadijeh Khanaliha 1 , Faezeh Haghighi 3 , Mahmood Faramarzi 1 and Morteza Haghighi Hasanabad 1, * 1 Research Center of Pediatric Infectious Diseases, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences, Tehran, Iran 2 Shahid Akbarabadi Clinical Research Development Unit, Iran University of Medical Sciences, Tehran, Iran 3 Cellular and Molecular Research Center, Sabzevar University of Medical Sciences, Sabzevar, Iran * Corresponding author: Research Center of Pediatric Infectious Diseases, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences, Tehran, Iran. Tel: +98-2166516049 Email: mhaghighi.v@gmail.com Received 2019 April 23; Revised 2020 March 01; Accepted 2020 March 04. Abstract Background: Pregnant women with Chlamydia trachomatis and Neisseria gonorrhoeae infections can vertically transmit these mi- croorganisms to their newborns through the birth canal and cause neonatal conjunctivitis secondary to sexually transmitted infec- tions. Objectives: In this cross-sectional study, we aimed to evaluate the prevalence of C. trachomatis and N. gonorrhoeae infections among pregnant women attending a hospital in Tehran, and also determine the vertical transmission rate of these two organisms to the eyes of newborns after vaginal delivery. Methods: Endocervical and conjunctival swabs were collected from pregnant women and their newborns within 24 hours after birth. Demographic and clinical data of participants were obtained using a questionnaire and from the hospital records. Then, DNA was extracted and tested by a multiplex PCR assay to detect C. trachomatis and N. gonorrhoeae in specimens. Results: Genital infections of C. trachomatis and N. gonorrhoeae were detected in 9.6% (11 of 125) and 1.6% (2 of 125) of pregnant women, respectively. Among newborns, ocular infection with C. trachomatis was detected in 2 (1.6%), and no case of N. gonorrhoeae infection was found. Both infected infants were born from asymptomatic infected women. Therefore, the vertical transmission rate of C. trachomatis infection was calculated as 18.1%. Our results also revealed that ocular C. trachomatis infection in neonates is significantly in association with genital C. trachomatis infection in pregnant women (OR = 0.16, 95% CI = 0.03 - 0.7, P = 0.002). Conclusions: Pregnant women with asymptomatic infection of C. trachomatis have a key role in the distribution of chlamydial conjunctivitis in newborns. Since ocular prophylaxis in neonates is not effective for chlamydial conjunctivitis, therefore education and screening of pregnant women, as well as treatment of infected cases, remain as the best approach for controlling the disease. Keywords: Chlamydia trachomatis, Neisseria gonorrhoeae, Vertical Transmission, Pregnant Women, Newborns 1. Background According to the WHO, annually, more than 330 mil- lion new cases of curable sexually transmitted infections (STIs) occur worldwide, which equals to about one million new infections every day (1). Chlamydia trachomatis and Neisseria gonorrhoeae are leading bacterial causes of the STIs with same symptoms among sexually active adults (2). Although infected women carry primarily the major bur- den of diseases associated with C. trachomatis and N. gon- orrhoeae such as mucopurulent cervicitis (MPC), gonococ- cal or non-gonococcal urethritis (GU or NGU), and pelvic in- flammatory disease (PID) with an increased risk of infertil- ity; they are also of concern as potential sources of neona- tal conjunctivitis secondary to STIs (3, 4). According to ev- idence, pregnant women with active, untreated infections of C. trachomatis and N. gonorrhoeae can transmit these bac- teria to their neonates during parturition with the risk of about 10 - 50% (5). Chlamydia trachomatis is the leading cause of vertically transmitted neonatal conjunctivitis with a peak of inci- dence during the spring and summer months (6). It is estimated that 20 to 50% of neonates with proven expo- sure to C. trachomatis will develop conjunctivitis after birth (7, 8). The clinical presentations of chlamydial conjunc- tivitis differ from mild symptoms to severe mucopuru- Copyright © 2020, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.