[Skip to content]

Private Healthcare UK
Search our Site

This website is certified by Health On the Net Foundation. Click to verify.
This site complies with the HONcode standard for trustworthy health information:
verify here.


Fetal blood sampling (FBS) in labour

Before you agree to have your cervical suture it is important to know all you can about it.


The information here is a guide to common medical practice. Each hospital and doctor will have slightly different ways of doing things, so you should follow their guidance where it is different from the information given here. Because all patients, conditions and treatments vary it cannot cover everything. Use this information when making your treatment choices with your doctors. You should mention any worries you have. Remember that you can ask for more information at any time.



What is the problem?

We think that the labour may be distressing your baby. We see signs of this by fetal monitoring. This test will tell us if your baby is all right.


What is fetal monitoring?

We use fetal monitoring during pregnancy and labour to check your baby’s heart rate and, therefore, how well your baby is. There are two types of fetal monitoring:


  • Intermittent monitoring - We do this using either a hand-held device, called a Sonicaid, or an instrument similar to an ear trumpet, called a Pinard stethoscope. We usually monitor your baby’s heart rate every 15 minutes in the first stage and every five minutes during the second stage of labour. If your baby has an abnormal heart rate during this type of monitoring, we will advise continuous fetal monitoring.
  • Continuous electronic fetal monitoring - We use a machine called a cardiotocograph (CTG) to continuously monitor your baby’s heart rate.


What is meant by distress?

Fetal distress is a term that describes a strain in the vital signs of your unborn baby. This could mean your baby is in danger. A common sign of fetal distress is an abnormal heart rate. If your baby is not coping well during labour, changes to your baby’s heart rate may be seen on the fetal monitor.


However, seeing changes in a baby’s heart rate is not uncommon during labour and may occur in babies that are not distressed. We need to do a fetal blood sampling (FBS) test to confirm whether or not your baby is in fact distressed.


Sometimes, before taking a fetal blood sample, we will take steps to try and improve the trace on the fetal monitor. These include:


  • changing your position, such as lying you on your left side or sitting you up
  • giving you more fluids if you are dehydrated
  • giving you drugs to reduce your temperature if it is high
  • stopping giving you drugs, if these are being used to start your labour or to increase your contractions.


If the trace on the fetal monitor does not show an improvement in your baby’s heart rate after taking these steps we will advise fetal blood sampling.  


What is fetal blood sampling (FBS)?

This test will confirm if your baby is suffering fetal distress. We usually take a sample of blood from your baby’s scalp. In the rare case of delivering a breech baby vaginally we may take the sample from your baby’s buttock.


We test the sample using a machine that shows the acid level of your baby’s blood. This level is called the pH. The result will be either within the normal range or low. If the result is low then the baby is ‘acidotic’; this tells us that the baby is suffering fetal distress from a lack of oxygen. If the result is below normal but your labour is progressing well, we will need to repeat the test if your baby’s heart rate stays abnormal on the fetal monitor.


If the result is very low we need to deliver your baby quickly. If you are in the first stage of labour this will be by Caesarean section. If you are in the second stage you will have an assisted delivery using forceps or suction.


What has gone wrong?

There are many possible causes of fetal distress that may lead the doctor to do an FBS. They are usually due to a lack of oxygen or poor circulation in the baby. They include:


  • Umbilical cord problems - A contraction can compress the umbilical cord reducing your baby’s oxygen for a short while. We use an FBS to confirm that your baby recovers after the contraction when the compression is released.
  • Placental insufficiency - In some pregnancies the placenta may be damaged or not well developed. The baby will not get enough oxygen during a contraction and this will be seen as an abnormal pattern on the fetal monitor.
  • Uterine hyperstimulation - This is when your uterus contracts very frequently. Your baby will receive much less oxygen from the placenta and will show signs of distress. An FBS will check that your baby is not becoming acidotic.
  • Bleeding from the placenta - Your placenta may bleed if it comes away from the wall of the uterus too early. This is called a placental abruption. If the bleeding is severe you may suffer with shock. This may also distress your baby, as it will not receive enough blood.


In some emergency situations an FBS is not advisable and we need to proceed straight to delivery. This will be by Caesarean section if you are in the first stage or by assisted delivery if you are in the second stage of labour.


The aim

The aim of fetal blood sampling during labour is to confirm whether or not your baby is in distress. It gives the doctors information on the state of your baby when we see an abnormal heart rate on the fetal monitor.


The benefits

If the test confirms that your baby is fine, you will avoid an unnecessary early delivery by Caesarean section or assisted delivery. If the test confirms that your baby is in distress, we can make an immediate decision to deliver before your baby comes to harm.


Who should not have an FBS?

You should not have fetal blood sampling if:


  • you are HIV positive or suffer from hepatitis B or C. There is a risk of passing these infections to your baby
  • because of the risk of your baby bleeding if we know your baby has a bleeding disorder
  • your baby is very premature - less than 34 weeks gestation.


What if you do nothing?

If you do not have an FBS but your baby’s heart rate is abnormal we will advise immediate delivery. If your baby is in distress but we do not deliver quickly your baby may suffer from a severe lack of oxygen. This can lead to permanent brain damage or even death.


There are situations where your baby can have an abnormal heart rate but is not in distress. By using FBS to confirm fetal distress we can be sure you and your baby are having the right treatment. You may avoid an unnecessary Caesarean section or assisted delivery to deliver your baby early.


Author: Dr. Chineze Otigbah MRCOG. Consultant obstetrician and gynaecologist.

© Dumas Ltd 2006

Get a quote

Looking for a quote or further information on a private birth?

If you are looking for a quote for a private birth, or want more information about private maternity services.

Complete the Private Births Enquiry Form....

Find a service

Find a private obstetrician

We maintain a database of around 2,500 UK consultants and specialists in private practice. You can search by specialty or postcode.

Search for a doctor....

Get a Quote

Private births

Get a quote now

Typical Costs

Private births

View typical costs

Obstetrician in your area

Private hospitals that can help

Private surgeons who can help