Growth & Doppler scans and IUGR (fetal growth restriction)

Medically written by Dr. Sushma Dhakal, MBBS · MD (Obstetrics & Gynaecology) · Fellowship in Fetal Medicine · Updated 30 October 2026 · 3 min read

In the second half of pregnancy, the key question is: is the baby growing well and getting enough oxygen and nutrition from the placenta? Growth and Doppler scans answer this. They are especially important for babies at risk of intrauterine growth restriction (IUGR), also called fetal growth restriction (FGR). Dr. Sushma Dhakal's MD research studied the risk factors and outcomes of IUGR.

What is a growth scan?

A growth scan measures the baby's head, abdomen and thigh bone to estimate fetal weight (EFW), and checks the amount of amniotic fluid. One scan shows the size; serial scans, usually 2–3 weeks apart, show whether the baby is growing along its curve.

What is a Doppler scan?

Doppler ultrasound measures blood flow. The main vessels checked are:

• Umbilical artery: shows how well the placenta is working.
• Middle cerebral artery (MCA): shows whether the baby is redirecting blood to protect the brain ("brain-sparing").
• Ductus venosus: helps judge how the baby is coping in severe early growth restriction.
• Uterine arteries: show the mother's blood supply to the placenta.

What is IUGR?

IUGR means the baby is not reaching its growth potential, usually because the placenta is not working well. It is commonly suspected when the estimated weight or abdominal size is below the 10th centile with abnormal Doppler, or below the 3rd centile. Not every small baby has IUGR: many are just constitutionally small and healthy. Doppler helps tell the difference.

Who is at higher risk?

• High blood pressure or pre-eclampsia, diabetes with vascular disease, kidney disease, anaemia.
• A previous baby with growth restriction or stillbirth.
• Smoking, very low maternal weight, or age over 40.
• Twins, and some infections or chromosomal conditions in the baby.

Warning signs to report

Most IUGR is found on scans, not by symptoms. But please contact your doctor promptly if you notice reduced baby movements, your bump seems small for dates, or you have headache, swelling or blurred vision, which can be signs of pre-eclampsia.

How is it managed?

There is no medicine that makes a baby grow faster inside the womb. Care focuses on careful monitoring and delivering at the right time, balancing the risks of staying in the womb against the risks of early birth:

• Regular growth scans, Doppler and CTG (baby heart-rate monitoring).
• Steroid injections to mature the baby's lungs, and magnesium sulphate to protect the brain, if early delivery is likely.
• Low-dose aspirin started early in pregnancy for women at high risk of pre-eclampsia can lower the risk.
• Delivery in a hospital with neonatal (NICU) care when needed.

With good monitoring, most growth-restricted babies do well.

Frequently asked questions

This guide is for general information only and is not a substitute for personal medical advice. Every pregnancy is different. Please consult your doctor about your own situation. In an emergency, go to the nearest hospital.

All guides

• What is an NT scan? A guide to the 11–14 week scan
• The anomaly (level II) scan: your 18–22 week detailed scan
• Amniocentesis & CVS: is it safe?
• Genetic counselling in pregnancy: who needs it and what happens
• Early pregnancy (dating) scan at 6–10 weeks: what to expect
• Fetal echocardiography: a detailed scan of your baby's heart
• Third-trimester well-being scan and biophysical profile (BPP)
• NIPT vs combined screening: which test is right for you?
• Twin pregnancy scans: chorionicity, TTTS and how often to scan
• Cervical length scan and preterm birth risk
• Fetal neurosonogram: a detailed scan of your baby's brain and spine