Monitoring the Baby
Baby Heart Rate Monitoring During Labour
Listening to the baby’s heartbeat has been a source of understanding the baby’s stress during labour for over a century. As much as labour is stressful to mums, it’s also very stressful for baby. The first means to carry out this activity was a trumpet-shaped stethoscope invented in the 19th century. The stethoscope is still in use across the world, but new technology now offers for other means of monitoring. Learn why the baby’s heartbeat needs to be monitored and the different ways to do this.
Why Monitor Baby’s Heartbeat?
Monitoring the baby’s heartbeat is one of the best ways to understand the baby’s condition. Labour can be a long process. Different factors can impact the baby’s safety during the hours of labour. Should the baby become distressed, this will show immediately in the heartbeat rate.
Intermittent Auscultation Monitoring
During early labour, doctors or midwives will listen at regular intervals with stethoscopes, known as intermittent auscultation, which usually is every 15 to 30 minutes. As labour continues, the intervals will become more frequent, especially as pushing begins. The intervals could be every five minutes or after every contraction. There are no risk factors associated with this process.
Doppler ultrasound, a technology commonly used in delivery rooms across the country, creates a continuous record of the baby’s heartbeat pre-birth. All that is necessary to create this record is to place two plastic disc sensors on the stomach, with a belt securing them around the waist. One sensor monitors the baby’s heartbeat while the other does the same for contractions. With a record of the heartbeat and contraction, this becomes a cardiotocograph (CTG).
CTG monitoring keeps the medical staff alert to any anomalies, assessing the baby’s health and stress levels. When contractions occur, a reduction in blood flow through the placenta occurs, which results in less oxygen for the baby. In most births, the baby has the ability to handle stress. Thus, it’s not uncommon for the baby’s heartbeat to slow during a contraction. Post-contraction, the heart rate goes back to normal.
Signs of Stress
There are instances when a baby does not cope with the stress of labour favourably. Signs of stress would include a more pronounced heart rate during contraction and continuing after it has passed. CTG helps detect these much faster than the manual intermittent auscultation. Care teams can interpret the CTG quickly to determine if the baby is in distress. On initial recognition of the heart rate’s pattern, the clinicians may recommend slowing down contractions or repositioning the mother. If those changes don’t help, an escalation may occur wherein delivery by caesarean section, forceps or vacuum assistance is required. The next steps of the medical personnel will depend on the stage of labour as well as the condition of mother and baby.
Fetal Scalp Electrode: Monitors Directly Adhered to Baby
While CTG is effective as a means to hear the baby’s heart beat in most situations, sometimes additional measures must be used. If the devices on the abdomen aren’t effective, a fetal scalp electrode, or clip, is an alternative.
The clip is a small device, attached to the baby directly via a vaginal examination. This tool is safe for mother and baby, however, for application, the water must be broken and the cervix dilated by at least a few centimetres. A fetal scalp electrode can not be used should there be any pre-existing maternal infection that could pass from mother to baby during birth.
Which Is Better: Intermittent Auscultation or Continuous CTG?
In cases of a routine birth with no risk factors, intermittent auscultation should be sufficient. It's also the least intrusive. When no risk is present, the benefits of CTG would be nominal.
If risk factors are present for mother or baby, continuous CTG is the better choice so that reactions can be quick in the event stress is evident. Risk factors for moms include pre-eclampsia (high blood pressure), diabetes, previous caesareans, multiple babies, a BMI (body mass index) of 40 or greater, and vaginal bleeding. For the baby, risks may be prematuriy. A CTG is also recommended in induced labour or if an epidural is administered.
Are There Advantages with CTG?
Any process used to listen to the baby’s heartbeat can be inconvenient to the mother, even intermittent auscultation. Mums are, of course, uncomfortable during labour, so everything is done to not to make it worse.
Intermittent monitoring via stethoscope may temporarily restrict the movement or position of the mother when finding the heartbeat. The internal monitoring may also fall at moments when mothers have the least mobility, which is during a contraction.
Continuous CTG monitoring restricts the mother more than intermittent auscultation, namely because she must be tethered to the machine. If mothers need to walk around, shower, or use the wash room, the nodes may need to be removed and reapplied.
There are no definitive answers on the perceived benefits of CTG. Although, some studies have found that routine use of CTG during labour can prevent serious, yet rare, complications. These studies have only sampled a small group. Thus, in any low risk situation, the benefit of continuous CTG is likely to be small.
Can CTG Increase the Need for Caesarean Sections?
There is no discernible data linking CTG monitoring to the increase in caesarean sections. CTG is, however, known to dispense false alarms around the baby’s heart rate pattern. If the physician is not sure about the baby’s status, a blood sample can be taken, called a scalp pH, to confirm the baby’s condition instead of just relying on the CTG. This could reduce the risk of caesarean section.
The Admission CTG
Upon admission, some centres perform a CTG. If all is normal and there are no known risk factors, the CTG nodes are removed. This is typically a precautionary practice. There has been no conclusive evidence that the admission CTG reduces adverse outcomes.
New Risk Factors
Even if mother and baby have been healthy throughout the pregnancy and haven’t expressed any risk factors, things can change during labour. Maternal fever could occur, as could bleeding. Should the labour be prolonged, this is another situation wherein CTG would be beneficial. Also, if the baby's heartbeat is noted as abnormal then a CTG should be used for extra precaution.
Should the care team make this decision, they should communicate why and respect the mother's decision should she prefer a different monitoring application. Mothers and care teams should discuss benefits or risks and come to the best decision for the health of both mum and baby.
Consult with your care team with any additional questions about monitoring the baby's heartbeat during labour.