<prompt> Denominator refers to:Pa of the presentation which lies over the Internal osRelation of different pas of fetus to one anotherBony fixed point of reference on presenting paPa of fetus lying in the lower segment of uterus  <response>: Denominator : It is an arbitrary bony fixed point on the presenting pa which comes in relation with the various quadrants of maternal pelvis. Denominators in different presentations : Occiput in veex Mentum in chin Frontal eminence in brow Sacrum Im breech Acromion in shoulder. Ref: Datta Obs 9e pg 70. 