Final answer:
The statement is true; lightening involves the fetus moving into the birth canal as it prepares for delivery, which is part of the childbirth process that includes several stages like dilation and expulsion.
Step-by-step explanation:
The question asks whether lightening occurs when the head of the fetus descends into the woman's pelvis as the fetus positions for delivery. This statement is true; lightening refers to the baby moving into the birth canal in preparation for delivery. During the childbirth process, the amniotic sac breaks, commonly known as the water breaking, and this usually signals that labor will begin soon. The stages of labor include cervical dilation, expulsion of the newborn, and afterbirth. The dilation stage is marked by the cervix dilating to about 10 cm, and during the expulsion stage, the baby descends through the birth canal, usually headfirst, and is born.