Normal Cervical Effacement in Term Labor

Abstract

Objective To estimate the natural history of cervical effacement in labor.

Study Design This is a retrospective cohort study of term, vertex, singletons who reached 10 cm of cervical dilation from 2010 to 2014. Interval-censored regression was used to estimate the median number of hours between changes in effacement (measured in centimeters of the residual cervix) and to estimate the median effacement at a given cervical dilation. Analysis was stratified by parity and labor type.

Results In total, 7,319 patients were included. Multiparas had faster effacement from 1 cm to complete effacement than nulliparas, but nulliparas were significantly more effaced at each cervical dilation. Patients in spontaneous labor had faster effacement and were significantly more effaced at each centimeter of cervical dilation than those who were induced or augmented. Once active labor was established (>6 cm of cervical dilation), 95% of patients had an effacement of 1 cm or less. By 8 cm of cervical dilation, 50% of all patients were completely effaced.

Conclusion There is a wide range in the normal length of time for the progression of cervical effacement. However, once a patient is in active labor, 95% of patients have effaced to 1 cm or less.

Keywords

effacement - labor - labor disorders - cervical effacement - first stage of labor - cervix

Note

This paper was presented in poster format at the 37th Annual Meeting of the Society for Maternal-Fetal Medicine, Las Vegas, NV, January 23–28, 2017.

• References

• 1 Zhang J, Landy HJ, Branch DW. , et al; Consortium on Safe Labor. Contemporary patterns of spontaneous labor with normal neonatal outcomes. Obstet Gynecol 2010; 116 (06) 1281-1287
• 2 Zhang J, Troendle J, Mikolajczyk R, Sundaram R, Beaver J, Fraser W. The natural history of the normal first stage of labor. Obstet Gynecol 2010; 115 (04) 705-710
• 3 Zhang J, Troendle JF, Yancey MK. Reassessing the labor curve in nulliparous women. Am J Obstet Gynecol 2002; 187 (04) 824-828
• 4 Vahratian A, Troendle JF, Siega-Riz AM, Zhang J. Methodological challenges in studying labour progression in contemporary practice. Paediatr Perinat Epidemiol 2006; 20 (01) 72-78
• 5 Spong CY, Berghella V, Wenstrom KD, Mercer BM, Saade GR. Preventing the first cesarean delivery: summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, and American College of Obstetricians and Gynecologists Workshop. Obstet Gynecol 2012; 120 (05) 1181-1193
• 6 Harper LM, Caughey AB, Odibo AO, Roehl KA, Zhao Q, Cahill AG. Normal progress of induced labor. Obstet Gynecol 2012; 119 (06) 1113-1118
• 7 Laughon SK, Zhang J, Troendle J, Sun L, Reddy UM. Using a simplified Bishop score to predict vaginal delivery. Obstet Gynecol 2011; 117 (04) 805-811
• 8 Langen ES, Weiner SJ, Bloom SL. , et al; Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Maternal-Fetal Medicine Units (MFMU) Network. Association of cervical effacement with the rate of cervical change in labor among nulliparous women. Obstet Gynecol 2016; 127 (03) 489-495
• 9 Huhn KA, Brost BC. Accuracy of simulated cervical dilation and effacement measurements among practitioners. Am J Obstet Gynecol 2004; 191 (05) 1797-1799
• 10 Holcomb Jr WL, Smeltzer JS. Cervical effacement: variation in belief among clinicians. Obstet Gynecol 1991; 78 (01) 43-45
• 11 Malapati R, Vuong YN, Nguyen TM. Reporting cervical effacement as a percentage: how accurate is it?. Open J Obstet Gynecol 2013; 3 (07) 4