<prompt> Commonest diameter of fetal head engagement isSubmentoveritcalOccipito frontalSuboccipito bregmaticMentoveical  <response>: The commonest diameter for fetal head engagement is suboccipitobregmatic, as it leads to veex presentation for normal vaginal delivery. Fetal skull diameters Measurements Suboccipitobregmatic Biparietal diameter Submentobregmatic 9.5 cm Suboccipitofrontal 10cm Occipitofrontal Submentoveical 11.5 cm Mentoveical 14 cm 