Assessing the risk factors before pregnancy of preterm births in Iran: a population-based case-control study oleh Maryam Soltani, Hamid Reza Tabatabaee, Shahin Saeidinejat, Marzieh Eslahi, Halime Yaghoobi, Ehsan Mazloumi, Abdolhalim Rajabi, Ali Ghasemi, Naeimeh Keyghobadi, Mostafa Enayatrad, Abed Noori, Seyyed Aliasghar Hashemi, Fatemeh Zolfizadeh, Sepideh Mahdavi, Tannaz Valadbeigi, Koorosh Etemad, Ali Taghipour, Cirruse Salehnasab, Mahmoud Hajipour