ABSTRACT
Objective:To analyze the duration of the second stage of labor without epidural anesthesia and its association with pregnancy outcome.Methods:This retrospective study involved 12 789 women who delivered without epidural anesthesia in the First Affiliated Hospital of Kunming Medical University from January 1, 2014 to December 31, 2017. These subjects were divided into primipara group (9 517 cases) and multipara group (3 272 cases). Demographic characteristics, maternal and neonatal outcomes and the duration of the second stage of labor were compared between the two groups using two independent samples t-test, Mann-Whitney U test and Chi-square test (Fisher's exact test). Differences in the maternal and neonatal outcomes were also analyzed among different subgroups in primiparae [length of second stage: <1 h group ( n=6 265), ≥1-2 h group ( n=2 305), ≥2-3 h group ( n=831) and ≥3 h group ( n=116)] and multiparae [length of second stage <1 h group ( n=3 144), ≥1-2 h group ( n=102) and ≥2 h group ( n=26)]. The association between second stage length and pregnancy outcomes was analyzed with Cramer's V. After adjusted for maternal age, gestational weeks at delivery, body mass index before pregnancy, complications during pregnancy and neonatal birth weight, the relationship between the duration of the second stage and adverse outcomes was analyzed by binary logistic regression analysis. Results:The 95 th percentile of the second-stage labor duration was 143 min for primiparae and 52 min for multiparae. The rates of vaginal delivery, forceps delivery, cesarean section in the second stage, episiotomy, third- or fourth-degree perineal laceration, postpartum hemorrhage, grade Ⅱ postpartum hemorrhage, transfusion, umbilical arterial blood gas pH<7.15 and transferring to neonatal intensive care unit (NICU) were all correlated with the duration of second stage in primiparae (Cramer's V values: 0.22, 0.23, 0.03, 0.22, 0.05, 0.10, 0.03, 0.03, 0.03 and 0.07, respectively, all P<0.05), and so did those of vaginal delivery, forceps delivery, episiotomy, postpartum hemorrhage, grade Ⅱ postpartum hemorrhage, transfusion and transferring to NICU in multiparae (Cramer's V values: 0.18, 0.19, 0.28, 0.14, 0.09, 0.13 and 0.06, respectively, all P<0.05). Logistic analysis showed that in primiparae, the duration of second stage >1 h was an independent risk factor for episiotomy, third- or fourth-degree perineum laceration, forceps delivery, postpartum hemorrhage, admission to NICU and umbilical arterial blood gas pH<7.15 [adjusted OR (95% CI): 2.080 (1.907-2.268), 1.773 (1.080-2.911), 1.625 (1.420-1.859), 1.365 (1.231- 1.514), 1.305 (1.165-1.462) and 1.246 (1.081-1.436), respectively], while second stage length >2 h was the independent risk factor for episiotomy, forceps delivery, third- or fourth-degree perineum laceration, postpartum hemorrhage, grade Ⅱ postpartum hemorrhage, blood transfusion, admission to NICU and umbilical arterial blood gas pH<7.15 [adjusted OR (95% CI): 4.844 (4.132-5.678), 4.223 (3.571-4.993), 3.289 (1.806-5.989), 1.952 (1.675-2.274), 1.781 (1.057-3.001), 1.654 (1.025-2.668), 1.682 (1.421-1.991) and 1.298 (1.039-1.620), respectively]. In multiparae, the length of second stage >1 h was an independent risk factor for episiotomy, blood transfusion, forceps delivery, postpartum hemorrhage and admission to NICU [adjusted OR (95% CI): 8.796 (5.717-13.534), 7.469 (2.874-19.411), 6.135 (3.217-11.699), 2.697 (1.624-4.477) and 1.814 (1.063-3.097), respectively], while the duration of second stage >2 h was the independent risk factor for episiotomy, third- or fourth-degree perineum laceration, blood transfusion, grade Ⅱ postpartum hemorrhage, forceps delivery and postpartum hemorrhage [adjusted OR (95% CI): 38.868 (14.948-101.063), 28.046 (2.780-282.490), 20.076 (5.384-74.866), 16.327 (3.406-78.274), 14.337 (5.351-38.411) and 9.036 (3.880-21.011), respectively]. Conclusions:The duration of the second stage of labor without epidural anesthesia is between that reported by Friedman and by Zhang. A prolonged second stage of labor may increase the risk of adverse pregnancy outcomes.