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Key takeaways

• Fetal growth restriction (FGR) means your baby's growth has slowed.
• Being small for gestational age (SGA) is not the same as FGR.
• Your baby's growth is routinely checked at antenatal appointments.
• If FGR is diagnosed, your baby will be closely monitored.

Understanding fetal growth restriction

Sometimes a baby's growth in the womb can slow down or stop. This is known as fetal growth restriction (FGR). It is sometimes called intrauterine growth restriction (IUGR). This means your baby is smaller and lighter than expected for their stage of pregnancy.

FGR is different from being small for gestational age (SGA). SGA means that your baby’s weight is estimated to be in the tenth centile. This means that if you have a group of 100 babies at the same stage in pregnancy, your baby would be one of the ten smallest ones. Most babies who are smaller than expected are healthy.

What causes FGR?

FGR affects up to 1 in 10 pregnancies. Sometimes, the cause of FGR is unknown. It can happen if the placenta is not working well. The placenta may not be giving your baby enough nutrients and oxygen.

Other reasons for FGR include:

• Factors related to your baby – such as a difference in your baby's genetic makeup (a chromosome or genetic abnormality).
• Infection – certain viruses, like cytomegalovirus (CMV) or toxoplasmosis, can cause FGR. Common colds or flu viruses are not linked to FGR.
• Your health – medical problems like high blood pressure or pre-eclampsia can affect placental function.

Who is at risk of FGR?

Several factors can increase the risk of FGR. These factors are linked to a baby's growth slowing down or stopping.

Risk factors include:

• Having had a small baby or pre-eclampsia in a previous pregnancy, or a previous stillbirth.
• Experiencing complications earlier in this pregnancy, such as heavy bleeding.
• Having existing medical problems such as high blood pressure or kidney problems. Other conditions like diabetes or heart disease can also increase risk.
• Smoking, drinking alcohol, or using illegal or recreational drugs.
• Being over 35 years of age.
• Having a measurement of your weight in relation to your height (body mass index, or BMI) below 20 or higher than 30.
• If you or your baby's father were small at birth.

Monitoring your baby's growth

Your baby's growth is checked at all your antenatal appointments from 26 weeks of pregnancy. This is a routine part of your care.

Your midwife will use a tape measure to check the size of your bump. They measure from the top of your womb (uterus) down to your pubic bone.

This measurement is recorded in your maternity notes and on a growth chart. If your midwife has any concerns about your baby's growth, they will refer you for an ultrasound scan.

This scan will usually happen within 72 hours. An ultrasound scan is a more accurate way to check your baby's size.

What to expect during extra monitoring

If your midwife or doctor thinks your baby might have FGR, you may have further tests.

These tests can include:

• Doppler ultrasound scan – this measures the blood flow through the umbilical cord. It checks the blood flow to your placenta and baby.
• Amniotic fluid assessment – this checks the clear liquid surrounding your baby in the womb.
• A tracing of your baby's heart rate – cardiotocograph, or CTG

These tests help your healthcare team understand how your baby is growing. They also check for any signs that your baby is not well.

If FGR is confirmed, you will need more scans to monitor the pregnancy closely. You may also be referred to a specialist for a more detailed scan.

Understanding Doppler scans

A Doppler ultrasound scan measures blood flow. This scan checks the blood flow through the umbilical cord. This helps your care team check on your baby's wellbeing and make sure they are getting everything they need from the placenta.

Doppler scans can also measure blood flow in your baby's brain and abdomen. More frequent growth scans and additional Doppler scans may be needed. These scans help your care team monitor your baby's wellbeing.

Care and support for fetal growth restriction

If your baby is diagnosed with fetal growth restriction (FGR), your care team will monitor you both more closely. It's important to understand that there is no treatment to reverse FGR once it has been diagnosed. It is not caused by what you eat or how much weight you gain during pregnancy.

The goal of this monitoring is to decide the best time for your baby to be born, ensuring their wellbeing.