Asynclitism

Asynclitism, or asynclitic position, refers to the position of the fetal head during labor. Asynclitic desribes an oblique presentation with the head tilted sideways so that a parietal bone enters the pelvic brim. With the baby's head is tipped towards one shoulder past early labor, the head and shoulder can then be an obstacle to descension past the ischial spines.

References:

1http://spinningbabies.com/baby-positions/all-positions/asynclitism