What change occurs to the shape of the uterus during placental separation?

During placental separation, the shape of the uterus changes from discoid to a more globular form. This occurs due to the process of uterine contractions that help facilitate the detachment of the placenta from the uterine wall. Initially, during pregnancy, the placenta has a discoid shape, closely adhering to the uterine lining. As the placenta separates, the contractions of the uterus cause it to retract and assume a more rounded, globular shape. This adaptation is essential for effectively expelling the placenta and minimizing the risk of retained placental fragments, which can lead to complications.

The other options describe changes that do not accurately reflect the physiological process during placental separation. While the uterus does undergo various changes throughout pregnancy and postpartum, the primary and notable transformation during the separation of the placenta is the shift to a globular configuration.