Abstract: Objective To explore the correlation between BMI before pregnancy and postpartum pelvic floor dysfunction in women undergoing vaginal delivery. Methods The pelvic floor muscle function of maternity were tested on 42-day-old after childbirth and questionnaire survey was conducted to collect relevant information. Chi-square test and Logistic regression were used to analyze the association between BMI before pregnancy and pelvic floor muscle dysfunction. The median effect of perineal laceration on the relationship between BMI before pregnancy and pelvic floor muscle dysfunction was analyzed by sequential test and sobel test. Results The incidence rate of pelvic floor muscle dysfunction in the women was 85.28%(1 112/1 304). After controlling of the confounding factors, such as body weight, gestational age, age, maternity education and birth times, the results of Logistic regression analysis were as follows: obesity before pregnancy increased the risk of pelvic floor type 1(OR=2.765, 95% CI:1.441-5.305)and type 2(OR=2.367, 95% CI:1.084-5.170)muscle dysfunction. The vaginal delivery of degree two and above perineal laceration increased the risk of pelvic floor type 1 (OR= 9.159, 95%CI:1.910-43.926)and type 2 (OR= 8.008, 95%CI:1.346-47.640)muscle dysfunction. Mediating effect analysis showed that the perineal laceration had an incomplete mediating effect on pelvic floor muscle dysfunction caused by obesity, and the mediating effect percentage was 25.43%. Conclusion Obesity before 山 东 大 学 学 报 (医 学 版)57卷2期 -黄凤艳,等.会阴裂伤在孕前BMI与产后盆底肌功能障碍关联性中的中介作用 \=-pregnancy and perineal laceration may be related to the occurrence of postpartum pelvic floor muscle dysfunction. The perineal laceration plays a partial mediating role in the risk of pelvic floor muscle dysfunction caused by obesity before pregnancy.

Key words: Perineal laceration, Obesity before pregnancy, Pelvic floor muscle dysfunction, Mediating effect, Association