 Even though much work has been invested in trying to identify risk factors that can predict which population will suffer from sphincter tears and other pelvic floor trauma, the epidemiology is still poorly understood. Factors that have been implicated to include operative vaginal delivery, birth weight, and primaparity. Up to this point little focus has been placed on antenatal factors that would help predict and prevent sphincter disruptions. At the time of birth the infants head is the largest part of the body. Thus, head circumference of the infant may be able to predict which subjects is more likely to suffer from sphincter disruption. Thus, this study aims to determine whether or not fetal head circumference measured antenatally is predictive of pelvic floor trauma. 