What term is used to describe the final phase of pregnancy and the beginning of the birthing process?

The term that describes the final phase of pregnancy and the beginning of the birthing process is "labor." Labor refers to the series of contractions and physiological changes that occur in a pregnant individual as the body prepares to deliver the baby. It's marked by the onset of regular uterine contractions that lead to cervical dilation and ultimately the delivery of the baby.

This term specifically captures the process that occurs just before delivery, making it distinct from related terms. For instance, "gestation" refers to the entire duration of pregnancy, from conception until labor begins, while "delivery" describes the actual birth of the baby. "Expulsion" typically pertains to the stage where the baby is expelled from the birth canal, which is a part of the labor process but not synonymous with it. Therefore, "labor" is the most accurate answer to describe the critical time leading up to childbirth.