Fig. 1From: Assessing the risk factors before pregnancy of preterm births in Iran: a population-based case-control studyStudy project locations in Iran. The population of the study was conducted on mothers that referred to a health care center in several provinces of Iran, including Fars, Hormozgan, Kermanshah, Hamadan, Kohgiloyeh, and Boyerahmad, Yazd, Southern Khorasan, Golestan, and city of MashhadBack to article page