Labour

Labour is the process through which a baby is delivered from a woman's uterus to the outside world. It involves several stages.

Labour is first associated with biochemical changes in the uterus and cervix. As these changes progress, a pregnant woman starts to experience uterine contractions and her cervix starts to open (dilate). The rupturing of foetal membranes, also known as 'water breaking', is generally one of the later stages of labour and usually happens once the contractions and dilation have started.

A pregnancy is considered to be 'term' if the baby is born around the 40^th week. An early term, or preterm, labour is one that takes place before the 37^th week, while a post-term labour doesn't take place any earlier than around the 42^nd week.

Labour can be classified into three main stages:

• First stage - when contractions first start and the cervix gradually opens (dilates);
• Second stage - when the baby is pushed into the outside world, and;
• Third stage - when the placenta, which provides the foetus with nourishment from the blood supply of the mother during the pregnancy, is delivered.

Labour is the delivery of the baby. 

Signs and symptoms

General

Every woman's experience of labour is unique, but some general signs and symptoms associated with labour may include:

• Strong, regular contractions;
• Progressive cervical dilation;
• A show (when the mucus plug sealing the cervical canal during pregnancy comes away and out);
• Water breaking - the amniotic sac containing the baby breaks open and the amniotic fluid drains out through the vagina. The fluid is normally clear to pale yellow in colour;
• Backache, and;
• An urge to go the toilet, caused by the baby's head pressing on the mother's bowel.

First stage

Latent phase

The latent phase is the point at which a woman first starts to notice regular uterine contractions. Uterine contractions help to thin, stretch and dilate the cervix.

Contractions experienced during the latent phase are distinct from the Braxton Hicks contractions felt by some women around their 26^th week of pregnancy. Braxton Hicks contractions, or 'false labour' contractions, are usually described as being irregular, infrequent and less intense than genuine uterine contractions. Braxton Hicks contractions don't cause the cervix to dilate.

Dilation of the cervix occurs gradually over the course of the latent phase and the cervix may dilate to around three centimetres by the end of this phase of labour.

The latent phase of labour is the most variable and for some women, it may last only a few hours while for others, it may last days. Some women may experience their 'water breaking' during this stage, which generally speeds up the labour process.

Active phase

The active phase continues on from the latent phase and is associated with the most rapid cervical dilation. This phase is marked by strong and painful contractions that tend to occur 3-4 minutes apart and last from 30-60 seconds at a time.

The cervix can dilate from around three centimetres up to eight or nine centimetres. This phase has a more standard course and lasts from 2-5 hours, lasting longer for first-time mothers. Once the cervix has dilated to more than three centimetres, it is referred to as 'established labour'.

Deceleration / Transition phase

The transition phase continues on from the active phase, but is associated with a slower rate of cervical dilation. For some women, there is a blurry distinction between the active and transition phases.

The contractions become more intense, painful and frequent during this phase and the baby continues its descent deeper down the birth canal while the cervix continues to dilate. Some women may experience shaking and vomiting through this phase.

Second stage

Once the baby is positioned in the birth canal and the cervix has sufficiently dilated to 10cm, the mother actively starts to push out the baby. This phase can be variable in its length, with first-time mothers potentially taking hours to deliver their infant, while experienced mothers may deliver within a matter of minutes. This is the most physically demanding stage.

Third stage

Once the baby has been delivered, further contractions help to push out the placenta. The placenta may be passed out immediately, or it may take up to 30 minutes. This stage is normally associated with moderate blood loss of up to 500ml.

This stage can be managed in one of two ways:

• Active management - this involves cutting and clamping the umbilical cord and administering oxytocin. Active management can ease blood loss and reduce the likelihood of serious complications, and;
• Expectant management - this involves a more passive approach, with the placenta being allowed to deliver on its own, using only gravity or nipple stimulation. In expectant management, the umbilical cord remains attached to the newborn until it has stopped pulsating.

Types of treatment

Pain relief

Breathing techniques

Some women may find relief by breathing slowly and deeply. Focusing on maintaining a slow and rhythmic breathing pattern may reduce the likelihood of holding your breath. Holding your breath increases the tension in your muscles and decreases the amount of oxygen you breathe in. Some women find it beneficial to chant words to help keep their breathing slow and rhythmic.

Massage

Some women may find relief by being massaged, especially if they are experiencing muscular tension and back pain. Massage oil may prove useful in providing a comfortable and relaxing massage to ease some of the pain and stress associated with labour.

Nitrous oxide gas

A mixture of oxygen and another gas called nitrous oxide can be self-administered through a mask. Nitrous oxide gas can reduce the feeling of pain and make it more bearable. Nitrous oxide gas takes about 15-20 minutes to be effective, so its use needs to be timed to coincide with the onset of a contraction. Side effects of the gas can include feeling light-headed, sick or sleepy.

TENS machine

A transcutaneous electrical nerve stimulation (TENS) machine is made up of four electrodes that are placed on the mother's back and a hand-held controller. The controller allows the mother to administer small and safe amounts of current through the electrodes that prompt the body to produce more of its own natural painkillers (called endorphins) and reduce the pain signals being sent to the brain.

Pethidine injection

An intramuscular injection of an opioid called pethidine may be offered during labour to ease pain and to aid relaxation. Pethidine may take up to 20 minutes to take effect and it can provide relief for between 2-4 hours.

Side effects of pethidine can include nausea and feeling unwell. If its effects are still present at the end of labour, it may make it more difficult for the mother to push out her baby. The baby's breathing may be temporarily affected by pethidine and it can potentially interfere with the baby's first feed after birth. Medication can be given to the newborn to block these side effects.

Epidural

An epidural is a local anaesthetic that is administered into the epidural space of the spinal canal for pain relief. During an epidural, the mother has an intravenous fluid (IV) drip inserted into a vein in her arm and an injection is administered into the spine to block pain impulses from the uterus to the brain.

An epidural takes about 10 minutes to set up and may take a further 10-15 minutes to provide pain relief. Once an epidural has been administered, there is ongoing monitoring of the baby's heart rate and the mother's uterine contractions.

Side effects associated with an epidural may include:

• Itchiness;
• A drop in blood pressure;
• A delay in the onset of the final stages of labour, which may result in the use of oxytocin;
• The decreased use of pelvic floor muscles, which may lead to the use of forceps to turn the baby, or even a caesarean section;
• The use of a catheter if the mother cannot urinate;
• Headache, and;
• Numb and tingling legs.

Induced labour

In some situations, labour may not be able to occur spontaneously and is instead induced. Some situations that may require labour to be induced may include:

• If the water has broken, but the labour has not started shortly after;
• If the mother has developed pre-eclampsia;
• If there are chronic or acute illnesses such as high blood pressure, diabetes or kidney disease;
• If the pregnancy has gone beyond the 42^nd week, and;
• For multiple pregnancies i.e. twin/triplets.

Membrane sweep

A midwife or doctor may insert their finger through the cervix and then sweep their fingers in a circular motion over the baby's head. This action can stimulate labour through the production of natural prostaglandins.

Synthetic prostaglandin

Synthetic prostaglandins are synthetic hormones that are administered by a gel or as a vaginal pessary. These hormones help the cervix to ripen and also help to induce labour.

In some women, prostaglandins alone can be enough to induce labour, but other women may also require oxytocin. There is a very small risk that using vaginal prostaglandin may result in overstimulation of the uterus, which may cause distress in the mother and her baby. Other possible side effects may include nausea, vomiting and diarrhoea and an allergic reaction to the gel.

Oxytocin

The body normally produces the hormone oxytocin to start and maintain labour contractions. A synthetic form of oxytocin can also start and maintain labour.

Oxytocin may be offered if a membrane sweep or prostaglandins haven't been able to start labour, or if the contractions are not yet strong enough. The waters need to have been broken before oxytocin can be administered. This can be done manually by the doctor if it has not occurred naturally. Oxytocin is administered through an intravenous (IV) drip.

As oxytocin intensifies the frequency and strength of contractions, the mother has not had the typical gradual build-up to the final stages of labour. Without this build-up, the mother's body has not had time to release endorphins, or natural painkillers and she can experience a higher level of pain and distress.

Oxytocin is also associated with possible overstimulation of the uterus, which can distress the baby.

Abnormal position

Most babies turn head-down between the 32^nd and 36^th week of pregnancy, which prepares them for delivery down the birth canal. When babies have not turned, or when they are positioned feet-first or bottom-first (breech position), a technique called external cephalic version may be performed.

During an external cephalic version, a doctor gently tries to turn the baby into the right position for delivery by applying pressure with their hands over the mother's abdomen. If successful, this technique can reduce the need for a caesarean delivery.

For more detailed information regarding foetal position during pregnancy, please refer to our report.

Episiotomy

An episiotomy is a cut that is made in the perineum, the area between the vagina and anus, to enlarge the vaginal opening for delivery of the baby's head (crowning stage). A local anaesthetic may be injected into the area before the cut is made. An episiotomy may be performed when extensive vaginal tearing seems likely, or if the baby is in an abnormal position. The incision is sewn up after birth.

Caesarean sections

When there are major complications with the baby and/or mother, a caesarean section can be the safest and quickest delivery option. During a caesarean section, the mother is first anaesthetised and an incision is made in the abdomen and the uterus, through which the baby is delivered.

Some of the more common reasons a caesarean section may be advised include:

• A prior caesarean delivery that has left the mother incapable of vaginal delivery;
• Birth defects;
• An underlying medical concern, such as diabetes;
• High birth weight of baby (i.e., over 4.5kg);
• The mother has a small pelvis;
• Low-lying placenta, and;
• Breech position.

Potential complications

Some of the potential complications associated with labour include:

• Preterm labour - this can increase the chance of the baby experiencing health problems;
• Prolonged labour - this may lead to infection if the amniotic sac has ruptured;
• Abnormal presentation - this is when the foetus is not in the favoured head-down position in the birth canal. Abnormal presentation increases the risk of injury to the mother and baby;
• Retained placenta - when the placenta has not been expelled within an hour after birth, and;
• Postpartum haemorrhage - heavy bleeding after the baby has been delivered.