Does Antenatal Fetal Head Circumference Predict Anal Sphincter Injury, a Prospective Study

• Fetal head circumference and position, maternal pelvis, infant weight, maternal weight, length of the second stage, the incidence of sphincter tears as diagnosed by transvaginal ultrasound as well as the incidence of fecal urgency and incontinence. [ Time Frame: 6 Months ] [ Designated as safety issue: No ]
  

• The magnitude of the effect of other factors such as maternal obesity, maternal age, duration of labor and pelvimetry on the risk of anorectal lacerations will be examined. [ Time Frame: 6 Months ] [ Designated as safety issue: No ]
  

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 infant's 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.