[Pressures on the human fetus during labor - intrauterine and on the fetal head (author's transl)].

During labor, the body surface of the fetus is subjected to strong pressure exerted by uterine contractions. In 40 cases, intrauterine pressure (IUP) which acts on the fetal body in the uterine cavity and pressure between the presenting part of the fetus and birth canal (PFB) which acts on the part of the fetus engaged in the birth canal were measured to determine the difference in pressure depending on the parts of the fetal body and their changes during the progress of labor. 1) Both peak IUP and PFB values increased gradually in the first stage of labor, and they became double in the period of labor with bearing-down efforts. 2) Since the peak value of PFB was 2.2 to 3.5 times higher than that of IUP, the part of the fetus engaged in the birth canal should always be subjected to 2.2 to 3.5 times more pressure than the intrauterine part of the fetal body. 3) Manual procedures such a vacuum extraction and Krysteller's compression on the uterine fundus increased the peak value of PFB markedly. The objective measurement of the pressure which acts on the fetal head during labor can be considered to contribute to the prevention of cerebral damage and fetal hypoxia.