Physiology and physiopathology of pregnancy and delivery

Vaginal delivery is a condition that represents a biomechanical challenge for allowing the progression of a neonate through the women's pelvis and pelvic floor. Several changes occur in the biomechanical women's characteristics through pregnancy with the aim of optimizing the mechanisms of childbirth and protect the mother's tissue from perineal trauma. The expulsion of the fetus begins by its descent into the pelvis depending on the pelvis axis and biometry, the fetus' size, its weight, and of the way of propulsion (uterine contraction and maternal pushing). Then, the fetus must progress through the pelvic floor, which induces a massive (up to 300%) elongation of pelvic floor muscles. Some obstetrician's interventions could improve the mechanisms of childbirth, including birth position and perineal manual protection; operative vaginal delivery increases the risk of perineal trauma at childbirth. Considering these biomechanical aspects may lead to a more individualized and efficient management of childbirth.