[Results with a new method for objectivation of rheobase measurements in normal pregnancy and risk of miscarriage or premature birth (author's transl)].

The rheobase (fundamental current strength), which can be used in obstetrics as a parameter of neuromuscular excitability, alters at the onset of labor, as Jung et al. first reported in 1969. It can be determined objectively to a considerable degree using the single-channel myograph manufactured by the Thönnies company, and an improved measuring method. Results of preliminary investigations can be confirmed which indicate that the rheobase in patients with premature labor and bleeding is lower than in women whose pregnancy is normal. Thus, where there is a risk of miscarriage or premature birth, neuromuscular excitability is increased. The fact that rheobase values in some patients who had undergone cerclage for cervical insufficiency are depressed indicates that the insufficiency is partly due to premature labor. It remains open to question whether etiology of the depressed rheobase is an indicator of increased neuromuscular excitability where there is a risk of miscarriage or premature birth.