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Vaginal birth

Station refers to the relationship of the fetal presenting part to the level of the ischial spines. When the presenting part is at the ischial spines the station is 0 (synonymous with engagement). If the presenting fetal part is above the spines, the distance is measured and described as minus stations, which range from −1 to −4 cm. If the presenting part is below the ischial spines, the distance is stated as plus stations (+1 to +4 cm). At +3 and +4 the presenting part is at the perineum and can be seen.

The fetal head may temporarily change shape (becoming more elongated or cone shaped) as it moves through the birth canal. This change in the shape of the fetal head is called molding and is much more prominent in women having their first vaginal delivery.

Cervical ripening is the physical and chemical changes in the cervix to prepare it for the stretching that will take place as the fetus moves out of the uterus and into the birth canal. A scoring system called a Bishop score can be used to judge the degree of cervical ripening to predict the timing of labour and delivery of the infant or for women at risk for preterm labour. It is also used to judge when a woman will respond to induction of labour for a postdate pregnancy or other medical reasons. There are several methods of inducing cervical ripening which will allow the uterine contractions to effectively dilate the cervix.

Vaginal delivery involves four stages of labour: the shortening and opening of the cervix during the first stage, descent and birth of the baby during the second, the delivery of the placenta during the third, and the 4th stage of recovery which lasts until two hours after the delivery. The first stage is characterised by abdominal cramping or back pain that typically lasts around half a minute and occurs every 10 to 30 minutes. The contractions (and pain) gradually becomes stronger and closer together. The second stage ends when the infant is fully expelled. In the third stage, the delivery of the placenta. The fourth stage of labour involves recovery, the uterus beginning to contract to pre-pregnancy state, delayed clamping of the umbilical cord, and monitoring of the neonatal tone and vitals. As of 2014, all major health organisations advise that immediately following a live birth, regardless of the delivery method, that the infant be placed on the mother's chest, termed skin-to-skin contact, and delaying routine procedures for at least one to two hours or until the baby has had its first breastfeeding.