5 things to know about monitoring the baby in labour:
- The baby’s heart rate can be monitored in labour as changes in this heart rate pattern can be an indication that the baby is not getting enough oxygen during labour.
- If you deliver at home, or on a midwifery led unit, then the midwife will listen in to the baby very regularly after a contraction during labour. This is called intermittent auscultation.
- If you deliver on an obstetric led unit, then you will be offered electronic fetal monitoring using a CTG machine.
- The CTG machine shows the baby’s heart rate and your contractions as two graphical lines.
- This allows continuous monitoring of the heart rate so that the pattern can be assessed over time.
Why do me and my baby need to be monitored
Labour can be a beautiful process, but to make sure that both you and your baby are safe in labour, then you will be offered monitoring of your baby. The safety of the baby in labour is monitored by listening to the baby’s heart rate. Changes in the baby’s heart rate can be an indication that the baby is not getting enough oxygen during labour and this is why monitoring is offered, so that serious changes can be detected and action taken.
How do medical professionals monitor my baby?
There are two ways of doing this. If your labour is midwifery led, and you are either at home, or in a midwifery led unit, this will be done by listening into the baby’s heart rate very regularly during labour. This is called intermittent auscultation.
Midwifery led monitoring:
Midwives will use a pinard stethoscope initially, which is small trumpet like instrument that rests on your abdomen followed by a Doppler ultrasound.
When your midwife listens using the Pinard, you won’t also be able to hear the heartbeat, but this is necessary to be certain that the heart rate that the midwife is hearing is your baby and not you.
For most of the labour, a Doppler ultrasound will be used. This is a digital and means that you can also heart the baby’s heart rate. This will be used to count the baby’s heart rate over one minute and in the UK, guidelines are that the midwives should listen for 1 minute following a contraction every 15 minutes during the first stage of labour, and then every 5 minutes in the second stage of labour. The midwife will then record the rate, and will also look for other features of the heart rate, such as it increasing or decreasing within that minute. A normal heart rate for a baby is between 110-160 bpm. The midwife will also be comparing the baby’s heart rate with the previous records to look for any big changes, as a baby’s heart rate should remain around the same throughout the labour. Your contractions will be monitored by the midwife palpating your abdomen.
Monitoring on an obstetric unit:
If you are delivering on an obstetric unit, then you will be offered electronic fetal monitoring using a CTG machine. CTG stands for cardiotocograph. This has two transducers that are strapped onto your pregnant tummy, one for the contractions and one for the baby’s heart beat.
These transducers connect via wires to a CTG machine, which converts the signals to a CTG trace, shown below. There are usually 3 lines on the screen. The lower line is the frequency and duration of the contractions. The top, more wiggly line monitors the baby’s heart rate. The middle line is the mum’s pulse which is monitored through a finger probe:
Discussing CTG’s and how they work:
Most hospitals now use an electronic screen to monitor the CTG rather than having a long print out of paper over time. The CTG allows the midwives and doctors to see the baby’s heart rate changes continuously over time.
CTGs are used to give an indication of the baby’s well being in labour. The CTG pattern will be regularly assessed to describe the baby’s baseline rate, any increases or decreases of the baseline rate above and below the average, and how wiggly it is. A normal fetal heart rate trace has an average baseline of between 110-160bpm, is very wiggly (described as normal variability) and does not have regular and frequent decelerations, or dips, of the heart rate below average. The trace above is normal. Increases of the heart rate above the line, known as accelerations, are a sign of a healthy fetus. Decelerations can be a concern, although they can also occur in many healthy babies in labour.
Monitoring the CTG pattern in labour is not an exact science. The main purpose is to screen for babies who are short of oxygen as a result of the physiological stress of labour. When the CTG is assessed, the doctors and midwives will describe the CTG as normal, suspicious or pathological. Depending on this assessment, they will choose to observe it further, or suggest a change to improve the CTG or, if the CTG is persistently pathological over time, suggest an action to deliver the baby. As a test, the is very sensitive but not very specific. This means it can often have patterns that might be concerning but for the most part the baby is actually fine. Whilst this means that it provides a very cautious way to monitor the baby, sometimes interventions in labour happen without the baby being unwell at all. There is not much good quality evidence to support the belief that the CTG improves outcomes in labour and reduces the chances of babies being born being short of oxygen. There is, however evidence that its use reduces the incidence of babies having seizures after birth (although this may not be associated with poorer long term outcomes (REF). The CTG is associated with higher rates of intervention in labour.
Although mostly it is possible to monitor the baby’s heart rate using the external transducers, sometimes, there is a lot of loss of contact on the CTG, which produces many gaps in the heart rate trace. This means that the quality of the trace is poor. Often the midwife will be able to improve this by moving the transducer but sometimes, you will be offered a small internal clip to be placed on the baby’s scalp in order to monitor the baby’s heart rate more clearly. This is a safe procedure to attach, although it can feel a bit uncomfortable to put it on. Once it is on, you won’t be able to feel it. Sometimes, this means that you can be more mobile in labour as you do not need to have the straps attached to an external machine. Some machines also offer the option of cordless monitoring, allowing more mobility in labour as there are no wires attached to a machine. You still need to have the straps to hold on the transducers though.
CTG’s vs ECG’s
A very small number of hospitals have an additional test in labour which measures the baby’s ECG. This is a slightly different measurement done in addition to the CTG. This also requires a clip on the baby’s head and is called “STAN’ which stands for ST Analysis. ST is a particular measurement taken from the CTG.
Discover more from Expert Pregnancy Safety Guidance & Maternity Advice | The Authentic Pregnancy Doctor
Subscribe to get the latest posts sent to your email.