Clinical features of long contraction wave recorded by an external tocodynamometer

Clinical features of a long contraction wave, lasting 3 minutes or more, recorded on an external tocodynamometer were studied. The long wave was observed in 50 out of 1,050 pregnant women. Clinical significance was not indicated by the shape of each wave which was either a long relaxing type or a fused type, but by the frequency of occurrence. Vaginal delivery and its close relation to oxytocin administration were significantly more frequent in the sporadic type, in which the long wave was observed once within a week, and fetal distress and a low Apgar score were more frequently observed in the frequent type, in which long waves occurred twice or more within a week. The results suggest that the obstetric prognosis is normal unless the long wave occurs sporadically and its recovery is good, and that it is ominous when long waves are observed twice or more within a week. Careful observation is needed in that case.