Baby’s Heart Rate During Labour
In most birth settings, your baby’s heart rate will be monitored during labour.
The idea behind fetal heart rate monitoring is to allow your care provider to see how your baby is coping during labour, and to identify potential problems ahead of time.
Fetal monitoring has been used universally during labour since the invention of the electronic fetal monitor (EFM) in 1958.
Developed for use in high-risk pregnancies, to help high-risk babies, EFM is currently used to monitor almost all women in hospital settings, regardless of the risk status of the mother.
What’s A Normal Heart Rate During Labour?
The normal range for a full term baby’s heart rate during labour is between 110 and 160 beats per minute (bpm). Higher or lower rates can be a sign your baby is having trouble coping with labour, depending on a number of factors.
There are several ways your baby’s heart rate is monitored:
- Doppler ultrasound: a small handheld tool placed on your belly, which transmits the fetal heartbeat.
- Fetoscope or Pinard: similar to the traditional stethoscope.
- Electronic fetal monitoring: two belts with small monitoring devices in them, which are placed around your belly; this method might be used continuously or intermittently.
- Internal fetal monitoring: a small electrode is inserted into your baby’s scalp; this can only be done once your water has been broken.
Most guidelines agree that intermittent monitoring (Doppler or Fetoscope monitoring) should be done every 15-30 minutes during active first stage of labour, and every 5-15 minutes during second stage of labour.
Electronic fetal monitoring (EFM) is used very commonly in most hospital settings. It can be used either intermittently or continuously. The recommended frequency for intermittent EFM is every 30 minutes during active first stage of labour, and every 15 minutes during second stage of labour.
Electronic fetal monitoring increases the likelihood of using vacuum or forceps during birth, and of c-section birth, and is not recommended for healthy women with uncomplicated pregnancies.
Different Kinds Of Heart Rates
Your baby’s heart rate will have what is called a baseline rate. This is the average fetal heart rate, taken during a 10 minute time period, with certain exclusions. The baseline heart rate gives your care provider an idea of what your baby’s heart rate should be during labour and how to determine if your baby is not coping.
If the baseline rate is less than 110 bpm, it is called bradycardia (abnormally slow heart rate). When the heart rate rises above 160 bpm, it is referred to as tachycardia (very rapid heart rate).
In certain situations, heart rate changes are considered a sign of fetal wellbeing. For example, when your baby moves his heart rate should increase.
Accelerations are normal rises in your baby’s heart rate – of at least 15 bpm, and lasting 15 seconds. These rises in heart rate usually happen at different stages during labour and birth. They indicate the baby has plenty of oxygen and is coping well.
If your care provider is worried about your baby’s wellbeing and hasn’t noticed any heart rate rises, they might try to induce accelerations by:
- Rocking your belly gently
- Pressing on the baby’s head, through the cervix, with their finger
- Delivering a short burst of sound to the baby.
When your baby’s heart rate drops temporarily, these are referred to decelerations. There are three types of deceleration:
- Early decelerations: these commonly happen when the baby’s head is compressed, usually just before birth, when the baby is descending through the vagina. They can also occur if the baby is in a breech position, as the head is being squeezed during contractions.
- Late decelerations: these begin at the peak of a contraction or just after a contraction has finished. They are smooth, shallow dips which mirror the contraction. If the baby’s heart rate doesn’t recover after the contraction then it is possible the baby isn’t handling labour well.
- Variable decelerations: these are irregular dips in the fetal heart rate that usually occur when the baby’s umbilical cord is being compressed. This happens during most labours and can be of concern if the pattern occurs repeatedly. The baby’s oxygen and other important nutrients might be compromised.
What Happens If Baby Isn’t Coping?
The main reason why care providers monitor baby’s heart rate during labour is to detect signs of fetal distress, which usually relate to baby’s supply of oxygen being compromised in some way. If this is detected early, care providers can intervene and potentially prevent complications such as cerebral palsy, seizures and death.
One complication is that there is no consensus on exactly how fetal distress is defined. Different care providers have their own definitions, depending on their professional experience, and they react to changes in fetal heart rates accordingly.
If your care provider picks up variations in your baby’s heart rate, it can be very frightening to hear there might be a problem with your baby’s wellbeing. Your doctor or midwife might decide to take a tiny sample of blood from your baby’s head, for testing. The oxygen levels in the blood sample will indicate how your baby is coping.
If possible, your care provider will try to ease your baby’s distress by:
- Ensuring you are well hydrated, which could mean giving fluids via IV.
- Having you change positions – especially if you have been reclining on your back, which puts the weight of the uterus on a major vein in your body.
- Making sure you have adequate oxygen levels.
If these changes don’t improve your baby’s heart rate, your care provider will advise that your baby should be born as quickly as possible. How your baby is born will depend on the stage of labour you are in, and how dilated your cervix is.
If you are fully dilated and your baby is very close to being born, it might be possible to birth vaginally with the help of forceps or ventouse. If you are still in active labour and your cervix is not fully dilated, your baby might need to be born by urgent c-section.
Fetal monitoring is common practice during labour and birth; however, it’s important to note that it’s your choice – as is the type of monitoring used. If you prefer to avoid electronic fetal monitoring, make sure you discuss this with your care provider during your pregnancy.
Recommended Reading: Unnecessary C-Section – How Can I Tell If I’ve Had One?