The first stage of labor is generally defined as starting when the effaced (thinned) cervix is 3 cm or 4 cm dilated. Women may or may not have active contractions prior to reaching this point. Rupture of the membranes or a bloody show may or may not occur at or around this stage.
This stage begins when the cervix is fully dilated, and ends when the baby is born. As pressure on the cervix increases, the Ferguson reflex increases uterine contractions so that the second stage can go ahead.At the beginning of the normal second stage, the head is fully engaged in the pelvis; the widest diameter of the head has passed below the level of the pelvic inlet.
Third stage is the period from just after the fetus is expelled until just after the placenta is expelled is called the third stage of labor.
In many cases, with increasing frequency, childbirth is achieved through caesarean section, rather than through vaginal birth.In the U.S. and Canada it represents nearly 1 in 3 (31.8%) of all childbirths, respectively.More than 22% of women undergo induction of labor and childbirth in the United States, doubling the rate in 2006 from 1990.Medical professional policy makers find that induced births and elective cesarean can be harmful to the fetus and neonate without benefit to the mother, and have established strict guidelines for non-medically indicated induced births and elective cesarean before 39 weeks.