1 Minute Read: Normal Labor and Delivery

With the Duchess of Cambridge being admitted to the Lindo Wing at St Mary’s Hospital, Paddington, London there is worldwide interest as to when the royal baby will arrive, especially as her husband the Duke of Cambridge was also born there.  Isabel Healthcare which produced the Isabel clinical decision support system for Health Professionals and the Isabel Symptom Checker has strong links with St Mary’s Hospital in Paddington as it is where Isabel Maude was treated, at age 3, with Necrotizing Fasciitis on the Pediatric Intensive Care Unit (PICU) after being misdiagnosed at her local hospital. It is where Jason Maude and Clinicians from St Mary’s conceived the structure of what became the Isabel clinical decision support system.  Further reading on how Isabel was developed can be found here.

Background and Overview:

Labor is the sequence of physiological events that results in a fetus being transported from the uterus through the birth canal to delivery as an Infant.  Labor is a clinical diagnosis where many things happen including:

• Changes in cervix ( lower part of uterus which connects with vagina) to allow passage of the fetus through the birth canal
• Synchronous, coordinated contractions of the cervix to produce the hormone Oxytocin which facilitates the  thinning of the cervix membranes and movement of the fetus into the vagina for delivery.  The Contractions progress in magnitude, duration and frequency as the labor progresses.

Labor is divided into three stages:

Stage 1 (Cervical stage): This occurs from onset of uterine contractions until full dilation of the cervix at 10 cms.  Stage 1 contains the latent phase where contractions are mild, short and irregular (less than 45 seconds).  The uterus contracts but there is little change in cervical dilation or effacement (thinning of the cervix).  The next phase of stage 1 labor is called the active phase which begins around the time of cervical dilation of 3-4 cm and contractions are strong, regular (every 2-3 minutes) and last longer than 45 seconds.

Stage 2:  This is from onset of complete cervical dilation (at 10 cms) to the time the Infant is delivered.  This stage is influenced by the 3 P’s: Passenger (Infant size and presentation), Passageway (size of pelvis and soft tissues), Power (uterine contraction strength).

Stage 3:  This stage occurs from when the Infant is delivered until delivery of the placenta.  This stage can be as quick as 10 minutes but can sometimes take up to 30 minutes.

The length of time it takes for these three stages to be completed varies for each woman.  Typically the lengths of the first 2 stages for women who have never given birth to a live infant before are significantly longer.

Symptoms of Labor:

• Intermittent low abdominal pain with or without low back pain, occurring regularly at least every 5 minutes.
• Each episode lasts 30-60 seconds.
• Sudden release of clear fluid from vagina or constant perineal wetness can represent rupture of membranes (rupture of amniotic sac the baby is in inside the body).  This can also be called “breaking of waters”. This may not happen until the fetus is in the second stage of labor.   Sometimes the waters can rupture prematurely before labor contractions start.  If you experience this release of clear fluid then you should contact your Obstetrician or Midwife.

It should be noted that patients in the third trimester (final three months of pregnancy) who have abdominal pain or vaginal bleeding should contact their Obstetrician or Midwife as vaginal bleeding is not associated with labor and could be an indication of abnormal labor complications such as placental abruption or placenta previa.

Physical Examination and Workup:

Once you have been seen by a Midwife or Obstetrician they will perform some examinations and tests to confirm you are in labor and what stage you are at:

• Assess fundal height – height of top of uterus to the top of the pelvic bone to determine fetal growth and development compared to number of weeks of pregnancy.
• Sterile pelvic exam to assess cervical dilation (how many centimetres dilated) and effacement how thin the cervix is) unless vaginal bleeding is present then the pelvic exam shouldn’t be performed.
• A complete blood count, type and screen should be sent.

The patient is assessed to correctly determine they are in labor and rule out other possible diagnoses which could explain their symptoms including:

• Braxton Hicks contractions (false labor) which are irregular uterine contractions without associated cervical changes and contractions can be every 10-20 minutes
• Muscoskeletal back pain
• Uterine ligament pain
• Other causes of abdominal pain including appendicitis, ovarian cyst or a urinary tract infection

Pain Control during Labor:

Various methods can be employed during labor to relieve pain and your Obstetrician or Midwife would have discussed these with you in your birth plan prior to being admitted in labor.

 Some common methods are:

• Self-help: learn about labor, how to cope with the pain, visit the antenatal unit where you may give birth.  Learn how to relax and stay calm.  Bring a partner, relative or friend with you.
• Gas and Air (Entonox) – This is a mixture of oxygen and nitrous oxide gas.  It won’t remove all the pain but can help to reduce it and make it more bearable.  It’s easy to use as delivered through a mouthpiece and you control how often you want to use it and when.  There are no harmful side effects to the baby but it can make you feel light-headed, sick, sleepy or unable to concentrate.
• Pain Killing Injections – Intramuscular injection into the thigh or buttock of a drug such as Pethidine can help you relax and lessen the pain.  After the injection is administered it can take 20 minutes to work and the effects last 2-4 hours.  The side effects can make you feel sick or woozy and  if the effect hasn’t worn off by the time you have to start pushing it can make it difficult to push in the second stage of labor.
• TENS – Transcutaneous Electrical Nerve Stimulation.  These can be hired or some hospitals have one you can borrow.  It’s most effective during the early stages of labor during the latent phase of stage 1 rather than the active phase.  Electrodes are taped onto your back and are connected to the machine or simulator.  You press a button on a handheld attachment which delivers small amounts of current through the electrodes.  It is believed to work by simulating the body to produce endorphins which are its own natural painkillers.  It also reduces the number of pain signals sent to the brain via the spinal cord.
• Epidural anaesthesia – An anesthetist in the hospital sets up an epidural (injection into lower back containing an anesthetic) which numbs the nerves which carry the pain impulses from the birth canal to the brain.  For most women, an epidural gives complete pain relief and can be helpful for women who have a long or painful labor.  Side effects can occur including drowsiness, sickness, make your legs heavy.  It can also prolong the second stage of labor as you can’t always feel the urge to push.

Labor and delivery is an amazing and exciting process which, after nine months of nurturing and protecting your growing baby – you finally get to meet them.