The upright and mobile positions during labor optimize uterine contractions and improve fetal alignment with the birth canal, facilitating effective descent. These positions enhance pelvic diameter, increase gravity-assisted fetal movement, and reduce maternal discomfort. Additionally, mobility promotes better maternal cardiovascular and respiratory functioning, which supports improved oxygen delivery to the fetus. Clinical evidence shows that such positions are associated with a shorter duration of labor and decreased need for instrumental delivery or cesarean section.

Reference: Williams Obstetrics, Cunningham et al., 25th Edition.