asynclitism

:  presentation of the fetal head during childbirth with the axis oriented obliquely to the axial planes of the pelvis Back pain or prolonged active labor is sometimes caused by a subtle malposition called asynclitism, in which the baby's head is tilted and the top of it isn't centered on the cervix.—Penny Simkin et al., Pregnancy, Childbirth, and the Newborn: The Complete Guide, 4th edition, 2010