. We studied the association of total duration of vacuum application and number of pulls and cup dislodgement with (1) primary outcome: the occurrence of major (subgaleal hemorrhage, skull fracture, and intracranial hemorrhage) or minor (cephalohematoma, scalp laceration more extensive than simple abrasions) neonatal head injuries and (2) secondary outcome: the occurrence of neonatal complications, including 5-min Apgar score <7, umbilical artery pH < 7