Mahboobeh Mousavi-Ramezanzade - 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
Yunes Jahani - Modeling in Health Research Center, Institute for Futures Studies in Health, Kerman University of Medical Sciences, Kerman, Iran
Moghaddameh Mirzaee - Modeling in Health Research Center, Institute for Futures Studies in Health, Kerman University of Medical Sciences, Kerman, Iran
Hamid Sharifi - 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

Background: A significant proportion of Female Sex Workers (FSWs) as a vulnerable population begin sellingsex at an early age, which may lead the person to develop sexually-transmitted infections (STIs) and humanimmunodeficiency virus (HIV). Thus, this study seeks to identify the factors which influence the age of firstsex for sale among the Iranian FSWs.Methods: In ۲۰۱۰, ۸۷۲ FSWs from ۲۱ centers in ۱۲ Iranian provinces were selected through multistagesampling and were interviewed individually by a standard questionnaire. Survival analysis of intervalcensored data was used to investigate factors which influence the age of first selling sex. The collected datawere analyzed using Weibull parametric model and the hazard ratio (HR) index was reported. The softwareemployed in this study was R version ۳.۴.۲ and icenReg package was used.Findings: The mean age of first selling sex was ۲۴.۹۴ ± ۷.۳۴ years. About ۲۲% of the participants started tosell sex before the age of ۱۸. The risk of experiencing the first selling sex was ۲۳% higher in those individualswho had experienced alcohol consumption (HR = ۱.۲۳) and ۵۱% higher in those who had drug injections(HR = ۱.۵۱). Also, age, education, and marital status were significant variables.Conclusion: In order to cope with the issue of first selling sex at an early age, the following strategies aresuggested: providing necessary trainings and building culture about the dangers of alcohol consumption anddrug injections, poverty reduction, facilitating education and marriage for young females, and combating sextrafficking

Sex workers, Age of onset, Iran, Survival analysis