Department of Obstetrics and Gynecology, San Gerardo Hospital, University of Milano-Bicocca, Monza, Italy.
Birth. 2011 Mar;38(1):30-5. doi: 10.1111/j.1523-536X.2010.00443.x. Epub 2011 Jan 4.
Cervical dilatation is commonly documented on a partogram indicating the expected rate of progress of labor. Although deviations from such a line can be used to indicate abnormal progress, what constitutes the "normal" rate of cervical dilation is still largely unknown. The objectives of this study were to assess the variability of the rate of cervical dilation in nulliparous women and to determine whether the rate of labor was independent of dilation on admission.
We analyzed a cohort of consecutive nulliparous women with spontaneous labor at term and singleton fetuses in cephalic presentation. Exclusion criteria were gestational age less than 37 weeks, induction of labor, or the presence of a uterine scar. Management of labor was standardized using set protocols of care. Active labor was diagnosed as regular contractions every 10 minutes or less, lasting more than 40 seconds, with cervical effacement more than 80 percent and dilation of 2 cm. Vaginal examinations were performed by a dedicated midwife every 2 hours. Amniotomy was performed for slow progress or arrest of dilation over 2 hours. Oxytocin was administered for arrest of cervical dilation for 2 hours with membranes ruptured. Data pertaining to cases ending in cesarean delivery were included up to the time of cesarean section.
The study sample comprised 1,119 women at 39.7 ± 1.1 weeks with an average duration of labor of 4.1 ± 2.4 hours. The rate of oxytocin use was 27 percent and of epidural analgesia 5 percent. The rate of oxytocin use was inversely related to cervical dilation on admission. Cesarean delivery was performed in 6 percent of women. Duration of labor at each centimeter of cervical dilation on admission showed a broad distribution (e.g., at 4 cm: median = 5.5, range: 0.8-12.5 hr). The rate of labor progression (expressed as the slope of the dilation-vs-time curve) was approximately 1.5 cm/hr, and it was essentially independent of cervical dilation on admission (r = 0.034, p = 0.267). A deceleration phase seemed to be present toward the end of the active phase of labor (approximately 9 cm).
In our setting, the rate of labor in nulliparous women at term was highly variable, and it did not appear to be affected by cervical dilation on admission.
宫颈扩张通常在产程图上记录，以表示分娩进展的预期速度。尽管偏离这种线可以用来表示异常进展，但宫颈扩张的“正常”速度仍在很大程度上未知。本研究的目的是评估初产妇宫颈扩张速度的可变性，并确定分娩时的宫颈扩张速度是否独立于入院时的扩张速度。
我们分析了一组连续的初产妇自发性足月分娩和头位胎儿的队列。排除标准为胎龄小于 37 周、引产或存在子宫疤痕。使用标准护理方案标准化分娩管理。活跃分娩被定义为每 10 分钟或更短时间出现一次规则宫缩，持续超过 40 秒，宫颈消失超过 80%，扩张 2cm。每 2 小时由专门的助产士进行阴道检查。如果 2 小时内扩张速度缓慢或停止，进行羊膜切开术。如果胎膜破裂 2 小时内宫颈扩张停止，给予催产素。包括剖宫产分娩结束的病例数据，直至剖宫产术。
研究样本包括 1119 名 39.7±1.1 周的产妇，平均分娩时间为 4.1±2.4 小时。催产素使用率为 27%，硬膜外镇痛使用率为 5%。催产素使用率与入院时的宫颈扩张呈负相关。6%的女性行剖宫产术。入院时每 1cm 宫颈扩张的分娩时间分布广泛（例如，4cm：中位数=5.5，范围：0.8-12.5 小时）。分娩进展速度（表示扩张与时间曲线的斜率）约为 1.5cm/h，且基本独立于入院时的宫颈扩张（r=0.034，p=0.267）。活跃分娩末期似乎出现减速阶段（约 9cm）。
在我们的环境中，足月初产妇的分娩速度变化很大，且似乎不受入院时宫颈扩张的影响。
