Baby’s heartbeat during pregnancy

Here is what to expect when you go in to hear your baby's heartbeat: your doctor will use a handheld doppler device or a Pinard stethoscope to find the baby's heartbeat. Next, he or she will do some calculations to determine the heartbeat and heart rhythm of your baby.

If you are hearing the heartbeat within the first eight weeks of pregnancy, the normal range to expect is 90-110 bpm. The baby’s heart rate goes up to 140-170 bpm for a short period between the ninth and 10th week of pregnancy. For the rest of the pregnancy, the accepted safe range for foetal heart rate is 110-160 bpm.

Listening to the baby's heartbeat isn't always easy. Sometimes, in the early weeks, doctors have difficulty finding the heartbeat. This could be because of the position of the baby, or because the mom-to-be is overweight or she has an anteverted uterus (a uterus that is naturally bent forward towards the tummy and over the cervix). All of these are normal conditions and don't yet signal a problem—your doctor will advise you on when to return to try and hear the foetal heartbeat again.

During pregnancy, foetal heartbeat and rhythm can help to assess if the baby has a health problem such as congenital heart disease. During labour and delivery, foetal heart rate can alert doctors if the baby is in some kind of distress; for example, inadequate oxygen supply.

The foetal rate slows down from about 170bpm at week 10 to about 130 bpm towards the end of the third trimester—this is normal. That said, some things that doctors keep an eye out for are:

Foetal tachycardia (heartbeat over 160 bpm for 10 minutes or more) can manifest as supraventricular tachycardia, among other conditions. This is a risk factor for hydrops fetalis or swelling (oedema) in the foetus that can be life-threatening.

Foetal tachyarrhythmia or fast and irregular heartbeat can manifest as atrial flutter, among other conditions. Foetal atrial flutter can increase the risk of premature birth and foetal death.

That said, foetal heart rhythm issues affect less than 2% of pregnancies, according to research published in the peer-reviewed journal Heart.

During pregnancy

There is some disagreement among experts about the lower normal limit of heart rate and rhythm in a foetus, but the widely accepted norm is 110-160 beats per minute.

If your doctor detects heartbeat under 110 beats per minute or over 180 beats per minute or consistently irregular cardiac rhythm, he/she may recommend a foetal echocardiogram to rule out heart problems.

During labour

During labour, the baby's heartbeat can change and give indications of how the baby is feeling. For example, the baby's heart rate may slow down very briefly during contractions—this is normal so long as the baby recovers quickly. A decrease in foetal heart rate during labour over a prolonged period—over 3 minutes or 5 minutes—could be cause for concern. On the other hand, a small and abrupt "acceleration" in the heartbeat—lasting a few seconds but never beyond 10 minutes—is nothing to worry about labour; indeed the FIGO sees it as a good sign that there is no hypoxia or acidosis.

Foetal heart monitoring during labour and delivery can save lives. Here's what to expect:

Once you are in hospital and your labour is established (cervix is dilated more than 3 centimetres and you are having strong regular contractions that are opening up your cervix even more), your doctor will want to monitor the baby’s heartbeat every 15-30 minutes in the first stage of labour and every 5 minutes in stage two of labour. This will be done in addition to monitoring your contractions.

This is important to gauge if the baby is having any difficulty during labour. Abnormal heartbeat or rhythm can alert doctors to problems early so they can intervene and try to prevent hypoxia/acidosis in neonates (perinatal hypoxia—or not getting enough oxygen just before, during or immediately after birth—is one of the major causes of death in newborns). There are two ways to monitor the baby’s heartbeat during labour:

• The baby’s heartbeat can be monitored intermittently, at intervals of about 15 minutes. This is done by a doctor using a Doppler foetal heartbeat monitor or a Pinard stethoscope. Though Doppler foetal heartbeat monitors are available over-the-counter, experts warn against overuse by eager parents-to-be and other non-medics, as inexpert use does not promote the mother or baby’s health.
• Alternatively, the mom-to-be could be hooked to an electronic device for continuously monitoring the baby’s heartbeat (continuous cardiotocography). This is done using an electronic foetal monitoring machine. Continuous monitoring may be done externally, using two transducers (pads) attached to your belly. Rarely, this may also be done by attaching a small electrode to the baby’s head via your vagina.
  Continuous foetal heart rate monitoring during labour is recommended in the following cases:
  • You have a fever (maternal pyrexia)
  • You have gone into premature labour (less than 37 weeks)
  • Your baby has been in the womb for over 42 weeks
  • You have had a difficult pregnancy or abnormal foetal growth
  • Your labour was induced or augmented with oxytocin, or there’s meconium in the amniotic fluid (also known as meconium-stained liquor, this could be a sign of foetal distress in a pregnancy up to 40 weeks) or a chance that you have “excessive uterine activity” 
  • Your baby is in a breech position (legs towards the cervix)
  • You have opted for an epidural (painkiller during labour)
  • You have high blood pressure
  • You have diabetes, heart disease or kidney disease
  • Your doctor detects a problem in the intermittent foetal heart rate check
  • You are carrying twins or more babies (twin or multiple pregnancy)
  • You have had a C-section (cesarean delivery) in your previous pregnancy
  • Your baby seems small, based on an external examination by the doctors and maternity nurses

During labour, the baby’s heartbeat is usually between 110 and 160 beats per minute. Check with your gynaecologist about the appropriate range for your baby, as it may be on the higher or lower side in different circumstances. In some cases, the baby’s heart rate may also fluctuate during contractions, but this is normal and doctors can respond quickly if they are already monitoring the heart rate.

Additionally, while measuring foetal heart rate in the intrapartum period—during labour and up to afterbirth, when the body expels the placenta—the internationally accepted guidelines of the  FIGO intrapartum fetal monitoring consensus panel say that “CTG (cardiotocography) monitoring should never be regarded as a substitute for good clinical observation and judgement, or as an excuse for leaving the mother unattended during labour.”

FIGO is the International Federation of Gynecology and Obstetrics.

Though foetal heart rate monitoring during labour and delivery is safe, there are ups and downs in all situations: a 1995 meta-analysis found that electronic intrapartum foetal heart measurement almost halved the instance perinatal (just before or after birth) death by hypoxia but significantly increased surgical intervention by way of C-section delivery or the use of forceps or vacuum to assist vaginal delivery.