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Vaginal delivery

Delivery may be accomplished by normal vaginal delivery, assisted vaginal delivery or Caesarean section.

Normal vaginal delivery

We always aim for a normal vaginal delivery in most cases. A normal vaginal delivery is associated with the least overall risks to the pregnancy except some scenarios. Scenarios which would increase risks of vaginal delivery includes placenta praevia (i.e. low-lying placenta over the cervical opening), previous Caesarean section or previous uterine surgery (e.g. myomectomy or removal of fibroids).

Stages of labour

Labour is defined as regular painful contractions with progressive cervical dilatation and effacement. 

There are 3 stages of labour:

1. First stage of labour is defined starts from the onset of regular painful contractions (each painful contraction may feel like a bad menstrual cramp and often lasts for 20-40 seconds in duration) and ends when the cervix becomes fully dilated at 10 cm. There are 2 phases of the first stage of labour:

Latent phase of labour which starts from the onset of regular painful contractions till the cervix is dilated to 5-6 cm and thin. This phase usually starts with painful contractions once about every 10-15 minutes, and usually lasts for about 6- 12 hours but may even lasts for 48 hours. During this phase, the pain is usually like menstrual cramps and starts off mild.

Active phase of labour starts from the time the cervix is dilated to 5-6 cm and thin to full dilatation at 10 cm. During this phase, the frequency of contractions starts would have increased to about once every 5 minutes, and then further increase to once every 2-3 minutes. The cervical opening, on average, is about 1 cm / hour. The pain increases in intensity and frequency as the labour progresses.

2. Second stage of labour starts when the cervical os is fully dilated to the time the baby is delivered. During the later part of this stage, the patient would be pushing in tandem with the contractions to deliver the baby. This phase usually lasts about 30 - 60 minutes but may even last as long as 3 hours especially if the patient is under epidural analgesia.

3. Third stage of labour starts after the baby is delivered and ends after the delivery of the placenta. Controlled cord traction of the placenta and an injection with syntocinon (oxytocin) allows quicker delivery of the placenta and reduce the risk of post-partum haemorrhage.

Figure 1 - Chart showing cervical dilatation with respect to time and the phases of labour

When to come to labour ward / delivery suite?

You are not expected to deliver before 37 weeks. Hence if you think that you have symptoms of labour before 37 weeks such as regular painful contractions, vaginal bleeding or leaking of liquor, come straight to the hospital. 

Once you have reached 37 weeks, come to the labour ward / delivery suite if you have any of the following symptoms or signs:

  • Regular painful contractions of about 1 every 5 minutes, or earlier if the pain is significant and you would require pain relief.

  • Leaking liquor - this manifests as leakage of usually colourless fluid from the vagina and is usually in moderate to large amounts and may occur in gushes.

  • Decreased fetal movement - you may want to count fetal movement from 28 weeks onwards. This may be achieved over any 2 hour period in a day where you are able to set aside time to focus on the fetal movement. The fetus usually moves predictably more in the evenings, and you may want to set aside 2 hours during the evenings to count the fetal movements. If the fetal movements is more than 10 times during that 2 hours, it is reassuring. Report to the hospital if the fetal movements is less than 10 times during the 2 hours. Often it is a false alarm, but it does make sense to have a check of the baby to ensure that the baby is healthy when the fetal movement is markedly reduced.

  • Show - this is blood mixed with mucus from the vagina, and usually in small amounts. Though this may precede labour, it is an unreliable predictor as to when regular painful contractions would start. Report to the hospital only if the vaginal bleeding is heavy or if you are still less than 37 weeks.

Episiotomy or not

An episiotomy is a surgical incision in the skin between the vagina and the anus. The use of episiotomy is highly controversial with supporters on both sides. Some of the possible advantages of episiotomies include speed up the delivery process, prevent ragged tearing of the skin between the vagina and the anus, etc. Possible side effects of episiotomy may include increased pain, increase in extension of the vaginal lacerations into the anal sphincter and / or anus, longer healing times, increased discomfort when intercourse is resumed.  I now do not do episiotomy routinely. I use my left hand to slow down the delivery of the head, my right hand to protect the perineal skin to minimise the skin tear, instruct the mother not to push when the head is crowning, and may consider doing episiotomy to the side if forceps delivery is done.

For patients without previous vaginal birth, perineal massage daily from 36 weeks have reduced episiotomies in the perineum during labour.  But there is no difference in the degree of tears in the perineum.  Others have used mechanical dilators (e.g. Epi-no) for the same purpose.

Assisted vaginal delivery (i.e. forceps or vaccum delivery)

When the cervix is fully dilated and the head of the fetus is low, and there is a reason for expediting vaginal delivery e.g. fetal distress, prolonged pushing and maternal exhaustion, assisted vaginal delivery by forceps or vacuum may be preferable to doing a Caesarean section in situations where it is judged that a successful forceps / vacuum delivery is safer than doing a Caesarean section where the head is already stuck low.

They are generally very safe when performed in such cases. The risks are generally higher if the head is higher, and lower when the head is lower.  Risks include:

Risks to the mother include increased tears in the vulva / vagina / rectum, bleeding and failure to deliver the baby vaginally which would then require the need for an emergency Caesarean section.

Risks to the baby from using a forceps may include soft tissue marks or abrasions over the head resulting from the forceps application, and rarely pressure on the facial nerve with weakness of the facial muscles which is usually reversible.

Risks to the baby using a vacuum may include slippage of the vacuum cup when applied on the head resulting in the need to use another forceps delivery or Caesarean section to achieve delivery, and rarely the risk of bleeding within the brain of the baby.

Whether a forceps or vacuum is used to assist vaginal delivery depends on the training / experience of the surgeon, position of the fetal head, and other factors. My favourite instruments are the Wrigley outlet forceps, the Neville Barnes forceps and the Kiwi vacuum cup for assisting vaginal delivery.


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