An in vivo comparative study of the pregnant and nonpregnant cervix using electrical impedance measurements.

Electrical impedance may be measured using electrodes on the surface of the cervix and recording the potential that results when an electrical current is passed. Increased hydration of the cervix has been described throughout pregnancy and occurs most dramatically before labour. This study compared tissue impedance measurements of the pregnant and non-pregnant cervix and found a statistically significant lower value (P < 0.001) in pregnancy. Further work may show that such measurements alter in relation to labour onset.