Identification of first-stage labor arrest by electromyography in term nulliparous women after induction of labor.

INTRODUCTION: Worldwide induction and cesarean delivery rates have increased rapidly, with consequences for subsequent pregnancies. The majority of intrapartum cesarean deliveries are performed for failure to progress, typically in nulliparous women at term. Current uterine registration techniques fail to identify inefficient contractions leading to first-stage labor arrest. An alternative technique, uterine electromyography has been shown to identify inefficient contractions leading to first-stage arrest of labor in nulliparous women with spontaneous onset of labor at term. The objective of this study was to determine whether this finding can be reproduced in induction of labor. MATERIAL AND METHODS: Uterine activity was measured in 141 nulliparous women with singleton term pregnancies and a fetus in cephalic position during induced labor. Electrical activity of the myometrium during contractions was characterized by its power density spectrum. RESULTS: No significant differences were found in contraction characteristics between women with induced labor delivering vaginally with or without oxytocin and women with arrested labor with subsequent cesarean delivery. CONCLUSION: Uterine electromyography shows no correlation with progression of labor in induced labor, which is in contrast to spontaneous labor.

Uterine electromyography for identification of first-stage labor arrest in term nulliparous women with spontaneous onset of labor.

OBJECTIVE: We sought to study whether uterine electromyography (EMG) can identify inefficient contractions leading to first-stage labor arrest followed by cesarean delivery in term nulliparous women with spontaneous onset of labor. STUDY DESIGN: EMG was recorded during spontaneous labor in 119 nulliparous women with singleton term pregnancies in cephalic position. Electrical activity of the myometrium during contractions was characterized by its power density spectrum (PDS). RESULTS: Mean PDS peak frequency in women undergoing cesarean delivery for first-stage labor arrest was significantly higher (0.55 Hz), than in women delivering vaginally without (0.49 Hz) or with (0.51 Hz) augmentation of labor (P = .001 and P = .01, respectively). Augmentation of labor increased the mean PDS frequency when comparing contractions before and after start of augmentation. This increase was only significant in women eventually delivering vaginally. CONCLUSION: Contraction characteristics measured by uterine EMG correlate with progression of labor and are influenced by labor augmentation.