During pregnancy a woman's uterus houses and protects the developing fetus for approximately 40 weeks. When the fetus has matured and labor begins, the baby goes through a series of movements that help it navigate through the birth canal. Occasionally, however, a baby may become "stuck" in the birth canal. This may occur if the baby does not attain the proper position, if labor ceases unexpectedly, or if the baby is too large to fit through the birth canal. In these situations, a vacuum extractor may be used to assist the delivery process. In order for vacuum extraction to be performed, a bell- or funnel-shaped cup is inserted into the vagina and placed on the baby's head. Suction is then applied to the cup using a manual or electric pump apparatus. The suction gently pulls the baby outward until the head has emerged from the birth canal. At this point the cup is removed and delivery proceeds as normal.