CJCP     2021 23 (12):  1242-1249    ISSN: 1008-8830  CN: 43-1301/R Risk factors for preterm birth: a prospective cohort study YE Chang-Xiang, CHEN Sheng-Bao, WANG Ting-Ting, ZHANG Sen-Mao, QIN Jia-Bi, CHEN Li-Zhang Department of Epidemiology and Medical Statistic, Xiangya School of Public Health, Central South University, Changsha 410078, China Received: 2021-08-04  Revised: null  Online: null Supporting info null