Fetal growth restriction (Intrauterine growth restriction)

Fetal growth restriction (FGR) is a condition where a baby is smaller than expected or when a baby’s growth slows or stops during pregnancy. It is also called intrauterine growth restriction (IUGR).

Babies are sometimes called small for gestational age (SGA) or small for dates (SFD).This is not the same as fetal growth restriction (FGR). Most babies that are smaller than expected will be healthy. 

FGR can cause problems during pregnancy or after your baby is born. Your baby will be closely monitored during pregnancy to make sure they have the very best care.

Up to 1 in 12 pregnancies (8%) will be affected by FGR.

What causes FGR?

Unfortunately, we don’t always know why FGR happens. 

These are some possible reasons:

  • It can be because the placenta isn’t working well. This stops your baby getting all the nutrients and oxygen they need to grow normally. 

  • Sometimes FGR can be the result of problems with the baby, for example chromosome or genetic abnormalities. These abnormalities mean that the baby does not grow normally even though the placenta is working ok.

  • Sometimes FGR is caused by infection with a specific virus. The commonest virus in the UK that can cause FGR is cytomegalovirus. It is important to note that common viral illnesses causing colds or flu are not linked to FGR.

There are several things that can increase the risk of FGR. The most common risks are:

If you have any bleeding during your pregnancy, with or without pain, it’s very important to get it checked out.

Risk factors for fetal growth restriction

These are some of the factors that are linked to baby’s growth slowing down or stopping.

Symptoms of fetal growth restriction

The main symptom of fetal growth restriction is the baby not being the size they should be for the stage of pregnancy that you are at. 

The baby’s growth is checked at all your antenatal appointments from 26 weeks. This is something that is done routinely (this means it is part of standard antenatal care). It’s one of the reasons why going to all appointments is very important.  

They’ll use a tape measure to check the size of your bump from the top of the uterus (womb) down to your pubic bone. This will be recorded in your maternity notes and on a growth chart. 

If your midwife has any concerns about the baby’s growth they will refer you for an ultrasound scan within 72 hours. 

This can be worrying but does not always mean something is wrong.  The scan is just a more accurate way of checking your baby's size. 

What should I do if I’m worried my baby bump is not getting bigger?

Try not to compare your baby bump to anyone else’s. If you are concerned about the size of your bump, call your midwife at any time. 

Risks of fetal growth restriction

FGR increases the risk of pregnancy complications and premature birth.

In the most serious cases, this can sadly include stillbirth.  

Almost half of all stillbirths in the UK are thought to be caused by FGR.  The risk is still low though – most babies with FGR will be born healthy. 

Treatment for fetal growth restriction

If there are concerns about growth, in most pregnancies this can be managed by monitoring your baby’s health and growth carefully, and planning an early delivery if needed to reduce the risk of complications.  

If your midwife or doctor thinks your baby might have FGR the blood flow through the umbilical cord will be measured by Doppler ultrasound scan. 

This measures the blood flow to your placenta and baby. You may have other tests to check the wellbeing of your baby too, such as an assessment of the amniotic fluid (the clear liquid that surrounds your baby in the uterus) during and a tracing of your baby’s heart rate, known as a cardiotocograph (CTG).  

After these tests, your healthcare team can tell you how your baby is growing and whether there are any signs that they are not well. If it is confirmed that your baby has FGR, you will need further scans to monitor the pregnancy more closely, until your baby is born. You may also be referred for a more detailed scan with a fetal medicine specialist.    

You may also be advised to take a low dose of aspirin (150mg) at night from 12 weeks of pregnancy until 36 weeks of pregnancy. This will not harm you or your unborn baby. 

Do not take aspirin in pregnancy unless it has been prescribed to you.

Your midwife or consultant (obstetrician) will talk to you about the best time to give birth. If your baby has FGR this is likely to be earlier than your due date.  

This may mean your baby will be premature.

Can I do anything to reduce the risk of FGR? 

If you have FGR it is unlikely to be because of anything you have done before or during pregnancy. Try not to blame yourself. Some things that increase your risk of having a small baby cannot be changed. 

There are some lifestyle changes you can make to reduce the risk of all pregnancy complications. They include:

  • stopping smoking 
  • taking vitamin D 
  • eating a healthy, balanced diet 
  • not drinking alcohol 
  • not using illegal drugs, especially cocaine 
  • going to all your antenatal appointments
  • taking any medications prescribed by your doctor if you have, or are at risk of, high blood pressure, diabetes or pre-eclampsia 
  • limiting your caffeine to 200 milligrams (mg) or under (around 2 mugs of instant coffee).

Use our caffeine calculator to check your caffeine intake

Monitoring your baby’s movements

It’s important to be aware of your baby’s movements during pregnancy, especially if there are concerns about your baby’s growth.

You will likely begin to feel your baby move between 16 and 24 weeks of pregnancy (in the second trimester).  

Get to know your baby’s movements. If you think that your baby’s movements have slowed down or stopped, contact your maternity unit immediately. There is always a midwife available 24 hours a day.

Do not wait until the next day.

Find out more about your baby’s movements in pregnancy.

Will FGR affect how I give birth?

If you have FGR you will be advised to give birth before your due date. This could be a few weeks before your due date. It is also likely to that you will be offered induction of labour.  Your care will depend on your individual circumstances.

You may be able to have a vaginal birth if there are no other complications.  Some babies are too small or weak to go through labour and vaginal birth though. In that case you may be advised to have a caesarean (C-section).  

If you're offered early induction of labour with continuous monitoring of your baby, your doctor may warn you that an emergency C-section is more likely.  Your healthcare team will talk to you about what your options are.

You may be advised to have your baby in a hospital that has a specialist baby unit (Neonatal Intensive Care Unit or NICU), just in case your baby needs extra care, especially if they’re very small and born early (prematurely). Not all small babies will need to go to NICU.

Depending on when and how you intend to have your baby, if you plan to give birth before 34 weeks of pregnancy, you will be offered a course of steroids (corticosteroids), which can help your baby with their breathing and reduce the risk of other health problems.  

If you give birth before 34 weeks, you might also be offered magnesium sulphate, which helps reduce your baby’s risk of cerebral palsy.  

After the birth

Your baby will be closely monitored after birth. because babies with FGR can be at risk of other complications after they are born.  

Some babies may need to spend time on a specialist baby unit (Neonatal Intensive Care Unit or NICU). 

But after your baby is born their growth will not be very different from other children. They are likely to catch up with their weight and growth within a year or so. 

Will FGR affect my next pregnancy? 

If you get pregnant again, your risk of having a small baby again is higher than it would be for other pregnant people. 

This may cause anxiety, but if you’ve had a small baby before your healthcare team will monitor you closely during your next pregnancy.

Your doctor may suggest that you take low-dose aspirin (150mg) at night once you’re 12 weeks pregnant.

If you need someone to talk to, you can call our midwives pregnancy line on 0800 014 7800 (Monday to Friday, 9am to 5pm), or email [email protected].

NHS (2014) Reducing stillbirth through improved detection of fetal growth restriction: A best practice toolkit.  www.england.nhs.uk/london/wp-content/uploads/sites/8/2019/11/Reducing-stillbirth-through-improved-detection-of-fetal-growth-restriction_-A-best-practice-toolkit.pdf

Pilliod RA, Page JM, Sparks TN, Caughey AB. The growth-restricted fetus: risk of mortality by each additional week of expectant management. J Matern Fetal Neonatal Med. 2019 Feb;32(3):442-447. doi: 10.1080/14767058.2017.1381904. Epub 2017 Oct 3. PMID: 28974133; PMCID: PMC6033681.

Jakubiec-Wisniewska K, et al (2022) Effect of Vitamin D Supplementation on the Fetal Growth Rate in Pregnancy Complicated by Fetal Growth Restriction. Children (Basel). 2022 Apr 12;9(4):549. doi: 10.3390/children9040549.

NHS England (2019) Saving babies’ lives Version two: a care bundle for reducing perinatal mortality. https://www.england.nhs.uk/wp-content/uploads/2019/07/saving-babies-lives-care-bundle-version-two-v5.pdf

NHS. Your baby’s movements. Available at: https://www.nhs.uk/pregnancy/keeping-well/your-babys-movements/ (Page last reviewed: 12 October 2021. Next review due: 12 October 2024) Accessed: 15 February 2023

Royal College of Obstetricians & Gynaecologists. Having a small baby. https://www.rcog.org.uk/for-the-public/browse-all-patient-information-leaflets/having-a-small-baby/

Vizzari G, Morniroli D, et al (2022) Postnatal growth of small for gestational age late preterm infants: determinants of catch-up growth. Pediatr Res. 2022 Dec 2; online ahead of print. doi: 10.1038/s41390-022-02402-3.

Royal College of Obstetricians & Gynaecologists (2013) The investigation and management of the small-for-gestational-age fetus: Green-top guideline 31. https://www.rcog.org.uk/media/t3lmjhnl/gtg_31.pdf

NHS England (2019) Saving babies’ lives Version two: a care bundle for reducing perinatal mortality. https://www.england.nhs.uk/wp-content/uploads/2019/07/saving-babies-lives-care-bundle-version-two-v5.pdf

Review dates
Reviewed: 12 December 2023
Next review: 12 December 2026