Gestational age was determined by the last menstrual period and confirmed by ultrasound examination, or by ultrasound examination alone if the sonographic determination of gestational age was not consistent with menstrual dating. Preterm PROM was diagnosed using a sterile speculum examination with documentation of pooling of AF in the vagina in association with a positive nitrazine test and/or positive ferning tests when necessary. Clinical chorioamnionitis was diagnosed when maternal temperature was ≥37.8 °C and two or more of the following criteria were present: uterine tenderness, malodorous vaginal discharge, maternal leukocytosis (>15,000 cells/mm3), maternal tachycardia (>100 beats/min), or fetal tachycardia (>160 beats/min) [59 (link)–61 (link)]. The diagnosis of acute histologic chorioamnionitis was made on the basis of the presence of acute inflammatory changes in the examination of the extra-placental chorioamniotic membrane roll and/or chorionic plate of the placenta using criteria previously described [62 (link),63 (link)]. Funisitis was diagnosed when neutrophil infiltration was detected in the umbilical vessel walls or Wharton’s jelly using criteria previously reported [64 (link),65 (link)]. Intra-amniotic inflammation was diagnosed when AF IL-6 determined ELISA concentration was ≥2,600 pg/ml [36 (link),39 (link),46 (link)]. MIAC was defined according to the results of AF culture. Intra-amniotic infection was defined as a combination of MIAC with intra-amniotic inflammation.