<prompt> Uterine contractions are clinically palpable when their intensity is more than :10 mm of Hg15 mm of Hg20 mm of Hg40 mm of Hg  <response>: The intensity of uterine contractions describes the degree of uterine systole. During pregnancy uterus is quiescent, the tone is 2-3mmHg. During the first stage of labor it varies from 8-10 mmHg, it is inversely propoional to relaxation. D.C.DUTTAS TEXTBOOK OF OBSTETRICS,pg no:117,7th edition 