Synchronization of Uterine Contractions Recorded by Guard‐Ring Tocodynamometer

The synchronization of local uterine contraction waves recorded by external tocodynamometers was studied and the following results were obtained: 1 When two guard-ring tocodynamometers were attached to the fundus and the caudal part of the uterus 20 cm apart, the synchronizing ratio of ascending points of the lower fifth of the contraction waves was significantly higher in the active phase than in the latent phase of labor. 2 Nearly regular upward or downward conduction of contractions between the fundus and the caudal part of the uterus was observed in each case. 3 The synchronizing ratio of peaks of small contraction waves was almost the same as the ratio in the active phase of labor. The results suggested the necessity of re-evaluation of the contraction curve recorded by the external tocodynamometer in view of the synchronization of contractions, instead of the amplitude, to control uterine contractions in preterm or term labor.