[Studies on the tocogram with bearing-down efforts during labor--analysis of the waveform and its clinical significance].

Together with a recording of external tocogram (Ex. toc.), intra-uterine pressure (IUP) and pressure between fetus and birth canal (PFB) were measured simultaneously and continuously, in 77 women during labor who were showing uterine contraction (UC) with bearing-down efforts (BDE). UC curves with BDE were analyzed to detect characteristic features and the sequence of their change in the second stage of labor. The following results were obtained. IUP curves were able to be classified into three types (Type A, B and C) according to the characteristics of the BDE waveform. This means of categorization was also able to be applied to the waveforms of PFB and Ex. toc., because those two pressure curves were essentially the same as that of IUP. Most of the type A contractions were observed early in the second stage of labor, and type B and C made their appearance successively. During the period of labor, from the first appearance of BDE on UC until the termination of the delivery, the mean frequency of UC with BDE was estimated to be 43 times in premiparae (Type A 5.8, Type B 19.7 and Type C 15.5 times) and 13 times in multiparae (Type A 2.0, Type B 2.7 and Type C 7.6 times). 3) Clinical significance from the point of view of parameters was as follows. The peak pressure of IUP increased slightly as labor progressed and the mean levels were 14.4kPa in Type A, 17.7kPa in Type B and 23.5kPa in Type C, respectively. PFB peak pressure, however, remained close to 50kPa in all cases irrespective of the type of curve. The mean BDE pressure was about a half the mean peak pressure for IUP and PFB respectively. The ratio of the levels of peak pressure of PFB and IUP (PFB/IUP ratio) were found to be approximately from 2.04 to 3.12. By a power spectrum analysis, the maximum levels of power in Type B curves were found at both 0.01 Hz and 0.2 Hz. The differential calculus curves estimated from IUP with BDE were able to be divided into three types, and the maximum value in Type B curves of IUP was 12.8kPa/sec. The IUP levels were plotted against those of PFB estimated from UC curves and the curve obtained indicated a straight line relationship. The levels of PFB were consistently two or three times higher than those of IUP.(ABSTRACT TRUNCATED AT 400 WORDS)