Abstract: Objective：To investigate risk factors of pelvic organ prolapse(POP) in early postpartum period among unipara women after vaginal delivery. Methods: From January to April 2017，a total of 1 216 primiparous women after vaginal delivery were recruited． Pelvic organ prolapse was assessed at 6-8 weeks postpartum，using the Pelvic Organ Prolapse Quantification(POP-Q) system. Logistic regression analysis was used to estimate the relative odds of each factor. Results: Of 1 216 participants, 52.96%(644/1 216) had prolapse to or beyond the hymen as POP group. There were significant difference at age, delivery pregnancy week, infant birth weight and forceps delivery between the two groups(P＜0.05). There were no significant difference at BMI before pregnancy, BMI when delivery, ponderal growth during pregnancy ,the second period of delivery, perineal tear and episiotomy between the two groups(P＞0.05). The results of nonconditional multivariate Logistic regression analysis showed that compared with the maternal age under 28, the incidence of early postpartum POP with older maternal age(≥36 years) was significantly higher(OR=2.352，P=0.010，95%CI：1.222-4.526); Compared with the infant birthweight under 3 000 g, women with infant birthweight 3 500-3 999 g and over 4 000 g had higher risk of early POP postpartum(OR=2.039，P＜0.001，95%CI：1.385-3.003；OR=2.676，P=0.007，95%CI：1.303-5.495, respectively). Women who had forceps deliveries were more likely to have POP than women who had natural deliveries(OR=1.760，P=0.019，95%CI：1.097-2.034). Conclusions: Postpartum POP is relevant to a variety of factors including theage, infant birthweight and forceps delivery. The incidence of postpartum POP among primiparous women after vaginal delivery was high. Early prevention for POP and training should be strengthened，specially for those who were at risk of POP.

Key words:  Pelvic organ prolapse, Pelvic floor, Visceral prolapse, Prolapse, Postpartum period, Primiparae, Natural childbirth, Risk factors