Fetal growth restriction !

The baby grows less than expected in the womb, most often because the placenta does not deliver enough oxygen and nutrients.

Updated 2026-11-01

Structures involved

Tap one to see what it is and open it in 3D.

Why it happens

What it is

Failure of the fetus to reach its genetic growth potential, usually defined as an estimated fetal weight or abdominal circumference below the 10th percentile for gestational age with signs of pathology, or below the 3rd percentile. It is distinct from a constitutionally small but healthy fetus.

Who gets it

Affects a significant share of pregnancies and is far more common in low- and middle-income countries. In Colombia and other Andean countries, high altitude, maternal undernutrition, anaemia and hypertensive disorders contribute. It is a major cause of stillbirth and low birth weight.

Causes

Placental insufficiency (most common): preeclampsia, abnormal spiral artery remodelling, placental infarcts
Fetal: chromosomal anomalies (trisomies), structural malformations, congenital infections (CMV, rubella, toxoplasmosis, syphilis)
Maternal: hypertension, diabetes with vasculopathy, kidney disease, antiphospholipid syndrome, undernutrition, anaemia
Toxic: smoking, alcohol, illicit drugs
Multiple pregnancy and high altitude

Risk factors

Previous growth-restricted baby or stillbirth
Chronic hypertension and preeclampsia
Smoking and substance use
Low pre-pregnancy weight and poor weight gain
Extremes of maternal age
Pregnancy at high altitude

Pathophysiology

When uterine and spiral arteries fail to remodel, placental blood flow falls and the fetus adapts by redirecting blood to the brain, heart and adrenals (brain sparing), so the head is relatively spared while abdominal growth slows. Reduced kidney perfusion lowers urine output and amniotic fluid. Progressive placental resistance leads to abnormal umbilical artery Doppler, then ductus venosus changes, acidosis and stillbirth.

Classification

Symmetric (early, often intrinsic fetal cause: chromosomal, infection): head and body equally small
Asymmetric (later, usually placental): abdomen small with relative head sparing
Early-onset (before 32 weeks) versus late-onset (32 weeks or later)

Symptoms and signs

Fundal height smaller than expected for gestational age
Reduced fetal movements
Often no symptoms; detected on routine ultrasound
Low maternal weight gain

Diagnosis

Clinical: Suspected when fundal height lags behind gestational age by more than a few centimetres or with risk factors; accurate dating from early ultrasound is essential.
Tests: Serial fetal monitoring (non-stress test, biophysical profile); screening for preeclampsia; testing for congenital infections and karyotype when growth restriction is early or symmetric.
Imaging: Ultrasound biometry (estimated fetal weight, abdominal circumference) with amniotic fluid assessment and Doppler of the umbilical artery, middle cerebral artery, ductus venosus and uterine arteries.

Differential diagnosis

Constitutionally small but healthy fetus (small for gestational age)
Wrong gestational dating
Oligohydramnios from ruptured membranes
Chromosomal or genetic syndromes

Goal of treatment

Find and treat the cause where possible, monitor fetal well-being closely, and time delivery to balance the risks of prematurity against the risk of stillbirth.

Treatment

Follow-up: Serial ultrasound for growth every few weeks, Doppler studies and fetal heart rate testing; frequency increases as Doppler worsens.
Lifestyle: Stop smoking, alcohol and drugs; improve nutrition and treat anaemia.
Medical: Treat maternal disease (hypertension, infections). Antenatal corticosteroids for lung maturity and magnesium sulfate for fetal neuroprotection when early delivery is anticipated.
Procedure: Planned delivery, by induction or caesarean, timed by gestational age and Doppler findings, with neonatal care available.

Complications

Stillbirth
Intrapartum hypoxia and caesarean delivery
Neonatal hypoglycaemia, hypothermia, polycythaemia
Meconium aspiration
Long-term: neurodevelopmental delay and adult cardiometabolic disease

Prognosis

Depends on the cause, the gestational age at onset and Doppler severity. Late-onset placental growth restriction usually has a good outcome with timely delivery; early-onset forms with abnormal Doppler, or with chromosomal or infectious causes, carry higher mortality and morbidity.

Prevention

Low-dose aspirin from early pregnancy in women at high risk of preeclampsia
Smoking cessation and good maternal nutrition
Early antenatal care with accurate dating
Screening and treatment of syphilis and other infections

Test yourself

Think of the answer, then tap the question to see it.

How is fetal growth restriction usually defined on ultrasound?

Estimated fetal weight or abdominal circumference below the 10th percentile for gestational age (or below the 3rd).

Which type of growth restriction suggests placental insufficiency?

Asymmetric, with a small abdomen and relative head sparing.

Which Doppler finding in the umbilical artery is ominous?

Absent or reversed end-diastolic flow.

What common clinical clue on antenatal exam suggests growth restriction?

Fundal height smaller than expected for gestational age.

Which neonatal metabolic problem is common after growth restriction?

Hypoglycaemia, because glycogen stores are low.

Add to my cards (5)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: Intrauterine growth restriction (MedlinePlus (U.S. National Library of Medicine), 2024).

← All conditions

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.

Uterine artery highlighted on the Durgical 3D model