Introduction: Gestational trophoblastic neoplasia (GTN) is a highly curable tumor arising from conception in the uterus. The purpose of this study is to investigate risk factors for the cancer among women with a molar pregnancy.
 
Materials & methods: This is a retrospective cohort study containing 200 women with molar pregnancy conducted between 2003 and 2013. Age at diagnosis, race, gravidity, parity, history of abortion, vaginal bleeding, gestational age, uterine height, β-human chorionic gonadotropin (β-hCG) during the first 28 days after uterine evacuation and status of catching to GTN were entered into analysis using the weibull model.
 
Findings: The mean of age in patients was 26.9±6.59. The mean and median of survival time were 7.84 and 8 weeks respectively. During the study, 32 patients were diagnosed with gestational trophoblastic neoplasia. The β-hCG growth variable from the first to the second week and the indicative variable which represented that the uterine height compared to the gestational age and was more than two were significant at 0.05.
 
Discussion & conclusions: The results of this study showed that the β-hCG growth variable from the first to the second week and the indicative variable which represented that the uterine height compared to the gestational age was more than two were the most important factors related to time to GTN for women with molar pregnancy.