[Assessment of degree of edema by means of bioelectrical impedance during pregnancy].

It is well known that the total body water in women with toxemia of pregnancy expands beyond the normally increased volume that characterizes pregnancy. Although abnormally increased water retention is usually diagnosed by both the edema of the legs and the weight gain, these methods are not quantitative. To quantify the degree of edema, we used bioelectrical impedance analysis (BIA). Because water and electrolytes are the dominant factors affecting electrical conduction in the body, the increase in total body water (the degree of edema) is assessed by BIA. BIA was conducted serially in a group of 38 normal pregnant women during pregnancy and 4 pregnant women with toxemia of pregnancy. The values for bioelectrical impedance in normal pregnant women decreased gradually during pregnancy, suggesting a physiological increase in total body water (p < 0.01). In contrast, the values for bioelectrical impedance dramatically decreased in the cases of 4 women with toxemia of pregnancy and accurately increased in the process of recovery from toxemia of pregnancy. These findings indicate that bioelectrical impedance analysis is a useful and practical method for assessing the increase in total body water.