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). Most babies that are smaller than expected will be healthy. But up to 10% of SGA pregnancies will be affected by FGR and will need close monitoring during pregnancy. In some cases, you may need to give birth earlier than expected.

What causes FGR?

FGR can happen when the placenta is not working well enough to provide the baby with the nutrients they need to grow normally. However, we don’t always know why FGR happens.

Sometimes it can be caused by other conditions, such as chromosomal problems or infections, such as cytomegalovirus or toxoplasmosis.

Is there anything that increases the risk of FGR?

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

• if you have previously had a small baby, pre-eclampsia or stillbirth
• if you have had complications earlier in this pregnancy, particularly heavy bleeding
• having a pre-existing medical problem such as high blood pressure, kidney problems, diabetes or heart disease
• smoking, drinking alcohol or using illegal or recreational drugs
• being over 35 years of age.

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

What does FGR mean for my baby?

If your baby has FGR, there is an increased risk of complications in pregnancy. Sadly, this can include stillbirth. But your healthcare team will monitor the baby’s growth and wellbeing closely to reduce the risk of this happening. They will also talk to you about the best time for you to give birth. This is likely to be earlier than your due date.

Being born early and small can also lead to complications after birth. This includes a higher risk of high blood pressure, coronary artery disease, type 2 diabetes and thyroid disease in later life. Some babies may need to spend time on a specialist baby unit (Neonatal Intensive Care Unit or NICU).

However, after your baby is born, their growth will not be typically different from other children. Having FGR does not mean they will be smaller than other children when they are school age.

Can I do anything to reduce the risk?

We don’t know why some pregnancies are affected by FGR and some are not. But it is unlikely to be related to anything you have done before or during pregnancy. It is important not to blame yourself.

Some things that increase your risk of having a small baby can’t be changed. But there are some things you can do to reduce the risk, including:

• stopping smoking
• taking vitamin D
• eating a healthy, balanced diet
• not drinking alcohol 
• not using illegal/recreational drugs, especially cocaine.

If you are overweight, you are more likely to develop high blood pressure, which can cause complications leading to problems with the baby’s growth. It can help to maintain a healthy weight before and during pregnancy.

If your doctor thinks you are at high risk of having growth restriction, they will advise that you start to take 150mg aspirin every night from 12 weeks of gestation until 36 weeks of gestation to reduce your risk of a small baby and pre-eclampsia.

What happens if my baby is small or not growing?

If your midwife or doctor thinks your baby might have FGR, you will be referred for an ultrasound scan to assess the growth of your baby. During this scan, there will be other tests to check the wellbeing of your baby. These include an assessment of the blood flow through the umbilical cord between the placenta and the baby (umbilical artery Doppler) and an assessment of the fluid around the baby (liquor volume).

Following this assessment, you will be advised how your baby is growing. If it is confirmed that your baby has FGR, you will have further regular scans to monitor the pregnancy more closely until your baby is born. The frequency of these scans will depend on the size of your baby and blood flow measurements in the umbilical artery, and may be performed in the fetal medicine unit or in antenatal clinic. You may also be asked to have a tracing of your baby’s heart rate, known as a cardiotocograph (CTG). Your healthcare team may also discuss the benefit of delivering your baby before your estimated due date (EDD).

If the umbilical artery Doppler test is abnormal, you may also be referred for a more detailed scan with a fetal medicine specialist.

Monitoring your baby’s movements

It’s very important to monitor your baby’s movements during pregnancy. Most women usually begin to feel their baby move between 16 and 24 weeks of pregnancy. A baby’s movement can be described as anything from a kick, flutter, swish or roll. There is no set number of normal movements. If you think that your baby’s movements have slowed down or stopped, it is important that you contact your maternity unit immediately. There is always a midwife available 24 hours a day. Do not wait until the next day to seek advice. This is particularly important if there are concerns about your baby’s growth during pregnancy.

Will FGR affect how I give birth?

The majority of women who want one will be able to try for a vaginal birth, if there are no other complications. But it is likely that you will be advised to give birth early. This may just be a week earlier than your expected date of delivery or it may be several weeks before, depending on how your baby is. Some babies may be too small to go through labour and a vaginal delivery, so you may be advised to have a caesarean section. Your healthcare professional will talk to you about what they think is best.

You may be advised to have your baby in a hospital where there is a specialist baby unit (Neonatal Intensive Care Unit or NICU). This is because your baby may need extra care, especially if they are very small and born early (prematurely). Not all small babies will need to go to NICU.

Depending on when and how you are going to have your baby, you may be offered steroids to help your baby’s lung development and reduce the chance of breathing problems after birth. You may also be offered magnesium sulphate, which is a medicine given before delivery to reduce the risk of cerebral palsy.

Will FGR affect my next pregnancy?

If you get pregnant again, the risk of having a small baby again is slightly higher. But you may be able to reduce your risk by trying to live a healthy lifestyle. It can help to:

• not smoke
• eat a healthy, balanced diet
• not drink alcohol
• not use illegal drugs or recreational drugs, especially cocaine
• work with your healthcare professional to make sure any long-term conditions, such as diabetes, are managed well.

In your next pregnancy, your doctor may recommend that you take low-dose aspirin (150mg) at night from 12 weeks of pregnancy.

Try not to worry too much if you want to get pregnant again. Your care will likely depend on what risk factors you have, but if you’ve had a small baby before, your healthcare team will monitor you closely during your next pregnancy.

More information

Click here for practical information from the Royal College of Obstetricians & Gynaecologists about carrying a small baby

www.bliss.org.uk is a UK charity that supports parents of babies born premature or sick