Original research article Early sex work initiation and its association with condomless sex and sexually transmitted infections among female sex workers in Iran Mehrdad Khezri 1, * , Mostafa Shokoohi 1,2, * , Ali Mirzazadeh 1,3 , Mohammad Karamouzian 1,4 , Hamid Sharifi 1 , AliAkbar Haghdoost 1 and Stefan D Baral 5 Abstract Early sex work initiation among female sex workers (FSWs) increases their vulnerabilities to high-risk sexual practices and sexually transmitted infections (STIs). We examined the association of early sex work with condomless sex indicators, HIV, and other STIs, including human papillomavirus, chlamydia, trichomoniasis, syphilis, and gonorrhea, among FSWs in Iran. We recruited 1347 FSWs from 13 cities in 2015, with 1296 participants (94.2%) reporting information about their age of sex work initiation. Early sex work was defined as the initiation of selling sex before 18 years of age. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were reported using multivariable logistic regression. Overall, 10.1% of FSWs reported early sex work initiation. FSWs who initiated sex work earlier were more likely to report last-month inconsistent condom use (aOR ¼ 3.31, 95% CI: 1.82, 6.02) and condomless sex with last client (aOR ¼ 1.72, 95% CI: 1.15, 2.56). There was no statistically significant association between early sex work and HIV (aOR ¼ 1.40, 95% CI: 0.43, 4.53) and any other STIs (aOR ¼ 1.01, 95% CI: 0.69, 1.48), except for chlamydia (aOR ¼ 2.09, 95% CI: 1.08, 4.04). These findings suggest that FSWs with early sexual debut would benefit from differ- entiated interventions including screening for STIs and enhanced counseling for condom use. Keywords Women, sex workers, high-risk sexual behaviors, sexually transmitted infections, HIV, Iran Date received: 26 November 2019; accepted: 17 February 2020 Introduction Female sex workers (FSWs) may initiate sex work at a young age. Literature has commonly defined early sex work as the initiation of exchanging sex for livelihood (such as money, drugs, shelter) before 18 years of age. 1– 3 Early sex work initiation is a common practice among FSWs as reported in both resource-rich and resource- limited countries. For example, Goldenberg et al. 1 using data from Canada showed that 38.0% (out of 508) of FSWs reported early sex work initiation, and Parcesepe et al. 3 using data in Kenya reported that 19.9% (out of 816) of FSWs reported involvement in early sex work. Research about the experiences of adolescents involved in sex work is limited globally, 4 in particular 1 HIV/STI Surveillance Research Center, and WHO Collaborating Center for HIV Surveillance, Institute for Futures Studies in Health, Kerman University of Medical Sciences, Kerman, Iran 2 Division of Social and Behavioural Health Sciences, Dalla Lana School of Public Health, University of Toronto, Toronto, Canada 3 Department of Epidemiology and Biostatistics, Institute for Global Health Sciences, University of California San Francisco, San Francisco, CA, USA 4 Faculty of Medicine, School of Population and Public Health, University of British Columbia, Vancouver, Canada 5 Department of Epidemiology, Key Populations Program, Center for Public Health and Human Rights, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA *These authors contributed equally to this work. Corresponding author: Mostafa Shokoohi, 155 College St., Toronto, ON M5T 3M7, Canada. Email: mostafa.shokoohi@utoronto.ca International Journal of STD & AIDS 2020, Vol. 31(7) 671–679 ! The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0956462420913431 journals.sagepub.com/home/std