The first stage of labor ends, and the second stage begins with complete dilation of the cervix to 10 cm. The start of uterine contraction signals the beginning of the first stage of labor. The delivery of the fetus marks the end of the second stage of labor. The delivery of the placenta marks the end of the third stage of labor. When the fetus is at zero station, the fetal head is positioned between the maternal ischial spines, and the fetus is said to be “engaged.” Zero station has no specific correlation with the stage of labor and, in fact, some pregnant patients may be at zero station for days to weeks prior to delivery.