Vaginal birth is the delivery of a baby from the uterus (womb), out through the vagina. Occasionally forceps or a vacuum device are required to assist, and this is known as instrumental delivery.
70% of Australian women have vaginal births, while 30% have caesarean deliveries. Of all women delivering babies in Australia:
58.1% had a spontaneous vaginal birth;
0.4% had a vaginal breech birth (baby is delivered bottom or feet first rather than head first);
3.5% were delivered using forceps; and
7.2% required vacuum extractions.
The entire process of labour and vaginal birth takes an average of 13 hours in women giving birth for the first time, and 8 hours in women who have given birth before. However, the exact duration varies a great deal from one woman to another. 18 hours of first stage is considered ‘prolonged’, and 1.5-2 hours of second stage is considered ‘prolonged’.
There are three stages of labour:
The first stage of labour is from the onset of labour until the cervix is fully dilated
The second stage of labour occurs from when the cervix is fully dilated till the delivery of the baby.
The third stage is from the delivery of the baby till delivery of the placenta and membranes.
What happens during vaginal birth?
First stage
On arrival at hospital, the general condition of the woman is assessed, including the vital signs of pulse, blood pressure, breathing and temperature. The condition of her baby is also checked with a monitor which measures the baby’s heart rate and the length and frequency of contractions of the uterus (CTG).
The woman is encouraged to empty her bladder regularly,and to eat and drink as desired throughout labour. She is also taught breathing techniques which focus on a long slow breath out and on relaxing with the breath out.
Moving around is generally encouraged during the first stage of labour, as this assists with the delivery progressing, and may help the woman to manage her pain.
In terms of preparation, there is no evidence that shaving of the pubic hair, or routine use of an enema (to empty the bowels) on admission has beneficial effects during delivery.
Confirmation of labour
The start of labour is identified by regular coordinated contractions (feeling of tightening with pain), which cause the cervix (neck of the womb) to become shorter (effacement), then dilate (open). There may be a ‘show’, when a small amount of blood stained mucous comes away from the cervix (though this may occur up to 72 hours before labour starts), or breaking of waters (ruptured membranes), with a gush of fluid from the vagina.
In 90% of cases, contractions start before the waters break. In 10% of cases, the waters breaking is the first sign of labour.
Labour is considered ‘term’ if it occurs from 37 weeks of pregnancy to 41 weeks. Babies born before 37 weeks are known as ‘preterm’. Some women go into labour extremely early, and their baby will require care at a specialist centre. The earliest a baby could survive early delivery if they are in a specialist centre is at 23-24 weeks of pregnancy, however there may be some long term health problems due to the fact it is not well developed before birth.
A doctor or midwife will confirm labour by doing a vaginal examination (inserting a gloved finger into the vagina) in order to check the dilation of the cervix, and whether the membranes have ruptured.
The criteria for labour are regular rhythmical contractions of the uterus (womb), causing cervical effacement (the progressive shortening and thinning of the cervix) and cervical dilation (the increase in cervical opening diameter). The doctor or midwife will also feel the tummy to check how low the baby’s head is in the pelvis, what position it is lying in, and which part of the baby is coming out first. This is called the ‘presentation’ and may be head first (also known as vertex), bottom/feet (or breech) or shoulder first.
Women who have been found to have group B strep (GBS) in their vagina (taken by routine vaginal and rectal swab at 36 weeks) will be given a penicillin injection while they are in labour. This is to reduce the risk of serious infections in the baby.
Monitoring the progress of labour
Once labour has been confirmed, the doctor/midwife will assess progress by monitoring:
changes in cervical effacement and dilation;
how far down the birth canal the baby’s head is;
the quality of contractions of the uterus; and
the wellbeing of the baby.
Second stage
Once the cervix is fully dilated (10cm), the woman is said to be in the second stage of labour. Once the baby’s head is on the perineum, the woman is encouraged to assume her preferred birthing position and to push. Contractions may decrease just prior to feeling the urge to push. During the actual pushing stage, the contractions are usually strong and forceful, and may be accompanied with a strong urge to push. This allows the woman to push in time with the contractions of the uterus. Most women feel an increased pressure in their lower back, perineum (area between the vagina and the anus) and rectum during this stage. To many women, the rectal pressure can feel the same as having a bowel movement. In some instances, the doctor may request the women delivers in the lithotomy position (lying on her back with her legs up in stirrups), so that he or she can access the area more easily to deliver the baby or carry out procedures or maneuvers.
Pushing
It is not clear what technique of pushing results in the best outcomes. Commonly, women are told to tuck in their chin, pull back their knees, take a deep breath, then bear down for 10 seconds, aiming to complete three pushes per contraction (3 sets of 10 seconds).
There is no evidence that this ‘coaching’ has any benefit over the woman pushing according to her urge to push (which is a reflex), pain of her contractions, and pressure felt from the baby’s head. If epidural anaethesia has reduced the sensation to bear down, coaching is likely to be required.
Pushing against a closed glottis is not generally recommended as it increases blood pressure in the mother, and does not carry an obvious benefit.
If the baby’s heartbeat is reassuring, and the woman is making progress, a woman having her first baby may continue pushing in second stage for up to two hours, or if she has an epidural in place (regional anasethesia) for up to three hours. If pushing lasts longer than this, there is risk to the baby and to the mother’s pelvic floor, so interventions to assist delivery (such as forceps or vacuum) may be required.
The delivery of the baby’s head is generally controlled in part by the doctor/midwife, who places their hand against the baby’s head to keep it flexed (chin towards the chest). The person assisting the delivery may ask the woman to pant or make only small efforts at pushing while the head is crowning, in an attempt to reduce the likelihood of a perineal tear. As the head is being delivered, the woman will feel a stretching or burning sensation. If needed, this process may be assisted by the use of forceps or a vacuum suction cup. If forceps are required, an episiotomy (surgical cut to make the opening of the vagina wider) may be carried out to make more room for the baby to be delivered.
Episiotomy is no longer carried out ‘routinely’. It should only be used when:
there is high risk of severe perineal tears;
the baby is getting stuck due to soft tissue blocking their exit (soft tissue dystocia); or
to speed up the delivery of a baby that is in significant distress.
Once the baby’s head is delivered, the doctor/midwife will feel around the neck for the umbilical cord. If the cord is present around neck, it will either be slipped over the baby’s head or doubly clamped, cut, and unwound from around the neck before the rest of the body is delivered. The rest of the body is generally easier to deliver, requiring more gentle contractions from the woman. The baby may be delivered up and directly onto the mother’s stomach so she can have a cuddle while waiting for the placenta to be delivered. This early ‘skin to skin’ contact helps successful breastfeeding, reduces crying, keeps the baby warm, and improves mother-baby interaction.
Traditionally the cord was clamped within one minute of the baby being delivered, which was mainly due to convenience. However, if cord clamping is delayed, more blood is transferred from the placenta into the infant. This is also the case if the infant is held below the level of the placenta before the placenta is delivered. Around 75% of available blood transfusion between the placenta and the infant occurs in the first minute after birth.
When the whole body is delivered, the woman enters the third stage of labour, during which the placenta is delivered.
Third stage
The delivery of the placenta only requires gentle pushing, and is usually much easier to deliver than the baby. It is essential that the doctor or midwife makes sure that the entire placenta is delivered, and that no parts are left behind, which may result in bleeding or infection.
There are two options for delivery of the placenta and membranes:
Expectant (passive, physiologic) management – the placenta is delivered naturally, without the use of drugs to contract the uterus (uterotonic agents), clamping the cord, or cord traction (gently pulling on the cord to assist delivery of the placenta); or
Active management- the cord is usually clamped early, there is controlled traction of the cord, and a drug (such as oxytocin) is given to cause the uterus to contract. The oxytocin is usually given as an intra-muscular injection while the baby is crowning, to reduce the risk of uterine atony (where the uterus does not contract down) which can cause large blood loss after the baby is born (post partum hemorrhage).
A large review studyfound that active management of the third stage of labour resulted in reduced blood loss from the mother, lower risk of postpartum hemorrhage (blood loss of more than 500ml), and reduced risk of prolonged third stage of labour. For this reason, the study concluded that active management should be the routine management of choice for women expecting to deliver a baby by vaginal delivery in a maternity hospital.
After delivery of the placenta, the whole process of labour is complete. The doctor/midwife will examine the placenta and the membranes to ensure that they are intact. The patient’s abdomen will also be felt to check that the uterus is contracting in order to stop the bleeding that occurs when the placenta is torn away.
The woman will also be examined for tears to the cervix or vagina. If present, these may need to be sutured (stitched). If an episiotomy was carried out, it will need to be sutured.
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Source: http://cholchetshare.net/archives/936
