NCIt definition : A fetal presentation where the head is presenting first in the pelvic inlet. Does
not apply if compound or breech presentation or if brow, face, hand, shoulder, etc.
present first in the pelvic inlet. (reVITALize);
Alternative definition : NICHD: A fetal presentation where the head is presenting first in the pelvic inlet.
Does not apply if compound or breech presentation or if brow, face, hand, shoulder,
etc. present first in the pelvic inlet. [verbatim from reVITALize];