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Key takeaways

• Fetal growth restriction (FGR) means your baby is not growing as expected.
• Routine antenatal checks monitor your baby's growth.
• Small for gestational age (SGA) is different from FGR.
• Ultrasound scans help understand your baby's growth.

What is fetal growth restriction and why is monitoring important?

A condition where a baby's growth slows or stops during pregnancy is called fetal growth restriction (FGR). It is sometimes called intrauterine growth restriction (IUGR). This means your baby is smaller and lighter than they should be for your stage of pregnancy.

Not all small babies have FGR. Some babies are naturally small and are born healthy. Others may catch up and grow later in pregnancy.

Monitoring your baby's growth is important. This helps to identify if your baby is not growing well. Because FGR means a baby might need extra support, regular checks are very important for their wellbeing.

If your baby has FGR, they will need close monitoring. This may mean planning for your baby to be born a little earlier to keep them safe and well. Going to all your antenatal appointments helps your midwife check your baby's growth.

The UK's screening process for fetal growth

Your baby's growth is checked routinely at all antenatal appointments. This usually starts from 24 or 26 weeks of pregnancy. Your midwife or doctor will measure your bump.

They will measure the distance from your pubic bone to the top of your womb (the symphysis fundal height, or SFH).

The SFH measurement is then plotted on a growth chart in your maternity notes. Many hospitals use personalised growth charts. These charts consider your personal characteristics, making checks more accurate.

The overall pattern of growth is more important than a single measurement.

The measurement should typically be around the same as the number of weeks pregnant you are. For example, at 25 weeks, it should be roughly 23-27cm.

This SFH measurement is a screening tool. It helps to find babies who might have a higher chance of a health problem.

It doesn't diagnose a problem, but it helps your midwife see if more checks are needed.

What happens if a problem is suspected?

If your midwife has concerns about your baby's growth, they will refer you for an ultrasound scan. This scan will usually happen within 72 hours.

This does not always mean something is wrong. The scan is a more accurate way to check your baby's size.

Small for gestational age (SGA) vs. fetal growth restriction (FGR)

It is important to understand the difference between 'small for gestational age' (SGA) and 'fetal growth restriction' (FGR).

A baby is called 'small for gestational age' (SGA) if they are among the ten smallest out of 100 babies at the same stage of pregnancy. Most SGA babies are healthy during pregnancy and at birth.

Fetal growth restriction (FGR) is different. It means your baby's growth has slowed or stopped.

This happens when the organ that passes nutrients and oxygen to your baby (the placenta) isn't working as well as it should. This might be due to the placenta itself. It can also be caused by an infection or another health condition.

It is important to find out if a baby has FGR so they can be monitored closely.

Investigating further with a growth scan

If your midwife has concerns about your baby's growth, you will be referred for an ultrasound scan. This scan provides a more accurate check of your baby's size. You may also be offered additional growth scans if you had FGR in a previous pregnancy.

During the scan, the healthcare team will take key measurements to assess your baby's size. They will also measure the blood flow through the umbilical cord to your placenta and baby (an umbilical artery Doppler scan).

Other tests may include an assessment of the liquid surrounding your baby in the womb (the amniotic fluid). You may also have a test that traces your baby's heart rate (a cardiotocograph, or CTG).

You may be referred to a specialist doctor (a fetal medicine specialist) for more detailed scans. This happens if your baby is very small, or if FGR is found early in pregnancy.

It also happens if the umbilical artery Doppler scan shows any concerns.

After these tests, your healthcare team will discuss how your baby is growing. They will also tell you if there are any signs your baby might need extra care.

Next steps if your baby is suspected to be small

If FGR is suspected, your baby's health and growth will be monitored carefully. You will need further scans and check-ups during your pregnancy.

You may be referred for a more detailed scan with a fetal medicine specialist. If your baby is very small and born early, they may need care in a specialist baby unit (Neonatal Intensive Care Unit, or NICU). Not all small babies will need to go to NICU.

Planning for birth

Your midwife or consultant will discuss the best time to give birth. If your baby has FGR, birth is likely to be earlier than your due date.

This may mean your baby is premature. You may be offered help to start your labour (an induction).

In some cases, your team may recommend that a caesarean birth (a C-section) would be a safer way for your baby to be born.

If birth is planned before 34 weeks of pregnancy, you will be offered special medicines (corticosteroids). These help your baby's lungs get ready for breathing. You might also be offered a medicine called magnesium sulphate, which helps to protect your baby's brain development.