Abstract: Objective  To explore the influencing factors and predictive models of electrophysiological abnormalities of pelvic floor in primiparas after vaginal delivery.
Methods  A retrospective analysis was performed on pregnancy and childbirth related data of primiparas who underwent regular antenatal examination, delivery and regular examination for rehabilitation of pelvic floor function at 6-8 weeks after vaginal delivery at People′s Hospital of Guigang City. The data of the parturient and the results of early postpartum pelvic floor detection were statistically analyzed, to ascertain the influencing factors and prediction models of electrophysiological abnormalities of the pelvic floor.
Results  Among the 664 primiparous women with vaginal delivery, there was an abnormal rate of type Ⅰ muscle fiver strength(70.03%) and of type Ⅱ muscle fiber strength(69.27%), as well as typeⅠand Ⅱpelvic floor muscle fiber fatigue(69.73% and 31.02% respectively), and abnormal vaginal dynamic pressure(92.02%). Maternal age, height, perineal lateral incision, perineal laceration, weight gain in the third trimester, duration of the second stage of labor, and newborn′s weight, newborn′s length, and gender were related to early electrophysiological abnormalities of pelvic floor of the primiparas after vaginal delivery. The greater maternal height, newborn′s length, and the second stage of labor of less than 3 h were protective factors. Weight gain during pregnancy had a significant impact on the electrophysiology of the pelvic floor. A receiver operating characteristic curve(ROC) of the weight gain during pregnancy and electrophysiological test results of pelvic floor was delineated to predict early electrophysiological abnormalities of pelvic floor in some parturients after delivery. In the early pregnancy, the area under ROC(AUC) of pregnant women with 25≤BMI＜30, abnormality of type Ⅰ muscle fiber strength and weight gain in the third trimester of pregnancy was 0.725(P=0.044, 95%CI: 0.523-0.927), and the optimal weight gain was 4.75 kg during third trimester.
Conclusion  The incidence of electrophysiological abnormalities in pelvic floor muscles is high in primiparous women after vaginal delivery. There are various influencing factors for early electrophysiological abnormalities of pelvic floor after delivery. Weight gain during pregnancy can predict early electrophysiological abnormalities of pelvic floor in some primiparas after delivery.

Key words: labor, birth canal, pelvic floor, electrophysiology, influencing factor