Prediction of preterm birth using vaginal polymorphonuclear count and it's ratio to epithelial cells in Iranian women

Prediction of spontaneous preterm delivery in Iranian women by comparing the vaginal polymorphonuclear call (PMN) counts on gram-stain preparations and ratios of PMN to epithelial cells (PMN/EPI) at second trimester of gestation. In a prospective case-control study, 110 cases with spontaneous preterm delivery at gestational age of less than 37 weeks were compared with control group of 110 women at term. Vaginal gram-stain preparations were collected at the first visit in 23-24 weeks of gestation and the cell counts were performed under oil-immersed microscope. To correct the intra-slide variations in cellular density, PMN/EPI ratios was calculated for each slide field. Mean delivery gestational ages were 34.5±3.5 and 39.4±1.2 weeks for the cases and the controls, respectively. There was a significant difference in PMN counts between the two groups (p=0.01). The mean PMN/EPI ratio, however, was significantly higher in case group (p=0.01). No significant difference was found in gravidity between the two groups. Different vaginal PMN count at second trimester were significantly associated with subsequent spontaneous preterm birth. However, the ratio of PMN of EPI count, was significantly higher in women with preterm birth at less than 37 weeks’ gestation.