1I.ee J, Kim JS, Park JW, et al. Chronic chorioamnionitis is the most common placental lesion in late preterm birth [J]. Placen- ta,2013,34(8) :681-689.
6Donders GG, Van CK, Bellen G, et al. Predictive value for pre- term birth of abnormal vaginal flora, bacterial vaginosis andaerobic vaginitis during the first trimester of pregnancy[J]. BJOG, 2009,116 (10) 1315-1324.
