Simic Marija, Cnattingius Sven, Petersson Gunnar, Sandström Anna, Stephansson Olof
Clinical Epidemiology Unit, T2, Department of Medicine Solna, Karolinska University Hospital and Institutet, Stockholm, SE 171 76, Sweden.
Department of Women's and Children's Health, Division of Obstetrics and Gynecology, Karolinska University Hospital and Institutet, Stockholm, SE-171 76, Sweden.
BMC Pregnancy Childbirth. 2017 Feb 21;17(1):72. doi: 10.1186/s12884-017-1251-6.
We sought to investigate the impact of the duration of second stage of labor on risk of severe perineal lacerations (third and fourth degree).
This population based cohort study was conducted in the Stockholm/Gotland region, Sweden, 2008-2014. Study population included 52 211 primiparous women undergoing vaginal delivery with cephalic presentation at term. Unconditional logistic regression analysis was used to calculate crude and adjusted odds ratios (OR), using 95% confidence intervals (CI). Main exposure was duration of second stage of labor, and main outcome was risks of severe perineal lacerations (third and fourth degree).
Risk of severe perineal lacerations increased with duration of second stage of labor. Compared with a second stage of labor of 1 h or less, women with a second stage of more than 2 h had an increased risk (aOR 1.42; 95% CI 1.28-1.58). Compared with non-instrumental vaginal deliveries, the risk was elevated among instrumental vaginal deliveries (aOR 2.24; 95% CI 2.07-2.42). The risk of perineal laceration increased with duration of second stage of labor until less than 3 h in both instrumental and non-instrumental vaginal deliveries, but after 3 h, the ORs did not further increase. After adjustments for potential confounders, macrosomia (birth weight > 4 500 g) and occiput posterior fetal position were risk factors of severe perineal lacerations.
The risk of severe perineal laceration increases with duration until the third hour of second stage of labor. Instrumental delivery is the most significant risk factor for severe lacerations, followed by duration of second stage of labor, fetal size and occiput posterior fetal position.
我们试图研究第二产程时长对严重会阴裂伤（三度和四度）风险的影响。
这项基于人群的队列研究于2008年至2014年在瑞典斯德哥尔摩/哥特兰地区进行。研究人群包括52211名足月头位阴道分娩的初产妇。采用无条件逻辑回归分析计算粗比值比（OR）和调整后的比值比，使用95%置信区间（CI）。主要暴露因素是第二产程时长，主要结局是严重会阴裂伤（三度和四度）的风险。
严重会阴裂伤的风险随第二产程时长增加而增加。与第二产程1小时或更短相比，第二产程超过2小时的女性风险增加（调整后比值比1.42；95%CI 1.28 - 1.58）。与非器械助产阴道分娩相比，器械助产阴道分娩的风险更高（调整后比值比2.24；95%CI 2.07 - 2.42）。器械助产和非器械助产阴道分娩中，会阴裂伤风险均随第二产程时长增加，直至少于3小时，但3小时后，比值比未进一步增加。在对潜在混杂因素进行调整后，巨大儿（出生体重>4500g）和枕后位是严重会阴裂伤的危险因素。
严重会阴裂伤的风险随第二产程时长增加，直至第三小时。器械助产是严重裂伤最显著的危险因素，其次是第二产程时长、胎儿大小和枕后位。
