<prompt> Conjugate of the diagonal is taken as a cm, then obstetric conjugate will bea 1 cma 2 cma - 1 cma - 2 cm  <response>: Obstetrical conjugateIt is the shortest distance between the sacral promontory and the symphysis pubisNormally, this measures 10 cm or more, but it cannot be measured directly with examining fingersThus, for clinical purposes, the obstetrical conjugate is estimated indirectly by subtracting 1.5 to 2 cm from the diagonal conjugate, which is determined by measuring the distance from the lowest margin of the symphysis to the sacral promontory 