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Intrauterine Growth Restriction (IUGR): Causes, Diagnosis, Management & Prevention Guide
Last updated: January 5, 2026
Introduction
Intrauterine Growth Restriction (IUGR), also known as Fetal Growth Restriction (FGR), refers to a condition in which a fetus fails to achieve its genetically determined growth potential. It is associated with increased risks of perinatal morbidity, mortality, and long-term health consequences. This guide provides evidence-based, clinically accurate, and compassionate information for both clinicians and families.
Definition and Terminology
IUGR is defined as an estimated fetal weight (EFW) or abdominal circumference (AC) below the 10th percentile for gestational age. It is essential to distinguish true growth restriction from constitutionally small but healthy fetuses, commonly classified as Small for Gestational Age (SGA).
Types of IUGR
- Symmetric IUGR: Proportionate reduction in fetal measurements; often linked to early gestational insults.
- Asymmetric IUGR: Head sparing with reduced abdominal growth; commonly due to placental insufficiency.
- Early-onset vs Late-onset: Early (<32 weeks) is more severe; late (>32 weeks) remains clinically significant.
Causes of IUGR
| Category | Examples |
|---|---|
| Maternal | Hypertension, preeclampsia, diabetes, renal disease, malnutrition, smoking |
| Placental | Placental insufficiency, infarction, abruption, abnormal cord insertion |
| Fetal | Chromosomal disorders, congenital infections, multiple pregnancy |
Diagnosis
- Ultrasound biometry: EFW, AC, HC, femur length
- Doppler studies: Umbilical artery, MCA, CPR, ductus venosus
- Fetal surveillance: NST and BPP
Management
Management is individualized based on gestational age, Doppler findings, and maternal-fetal condition.
Summary Table: Diagnosis and Management
| Step | Tool | Purpose |
|---|---|---|
| Screening | Ultrasound biometry | Identify EFW <10th percentile, assess AC/HC |
| Doppler | Umbilical artery, MCA, CPR, ductus venosus | Detect placental insufficiency and stratify fetal risk |
| Surveillance | NST, BPP | Monitor fetal wellbeing weekly or biweekly |
| Intervention | Antenatal corticosteroids, magnesium sulfate | Prepare for preterm delivery and fetal neuroprotection |
| Delivery | Induction or cesarean section | Timing guided by Doppler findings and gestational age |
Updated Research Insights (2024–2025)
- ACOG 2024: Defines FGR as EFW or AC below the 10th percentile and emphasizes umbilical artery Doppler as the primary surveillance tool.
- RCOG 2024: Differentiates SGA from FGR; recommends customized growth charts and delivery at 37 weeks if Dopplers are normal.
- WHO 2025: Highlights simplified screening and maternal nutrition strategies in low-resource settings.
- FIGO 2025: Advises delivery when ductus venosus Doppler shows abnormal a-wave; notes long-term cardiovascular risks.
- DGGG/OEGGG/SGGG 2024: Recommends structured neonatal neurodevelopmental and metabolic follow-up with family counseling.
Frequently Asked Questions (FAQs) About IUGR
1. What is intrauterine growth restriction (IUGR)?
IUGR, also called Fetal Growth Restriction (FGR), is a condition where a fetus does not grow as expected for its gestational age. It is usually diagnosed when the estimated fetal weight (EFW) or abdominal circumference (AC) is below the 10th percentile.
2. Is IUGR the same as small for gestational age (SGA)?
No. SGA refers to babies who are smaller than average but otherwise healthy. IUGR indicates impaired fetal growth due to underlying maternal, placental, or fetal issues and often requires closer monitoring.
3. How is IUGR diagnosed during pregnancy?
Diagnosis is made using ultrasound biometry to measure fetal size and Doppler studies (umbilical artery, middle cerebral artery, cerebroplacental ratio, ductus venosus) to assess placental function and fetal wellbeing.
4. What are the common causes of IUGR?
Common causes include maternal conditions (hypertension, preeclampsia, diabetes), placental insufficiency, malnutrition, smoking, infections, or certain fetal and chromosomal abnormalities.
5. Can IUGR affect the baby after birth?
Babies with IUGR may have low birth weight, hypoglycemia, or temperature instability. Some may require special neonatal care and follow-up for growth and development.
6. How is IUGR managed during pregnancy?
Management focuses on close monitoring of fetal growth and wellbeing through ultrasound and Doppler studies. Maternal health is optimized, and delivery timing is individualized based on fetal and placental status.
7. When should medical care be sought for suspected IUGR?
If reduced fetal movements or concerns about fetal growth occur, it is important to consult a qualified healthcare provider promptly. Regular antenatal care is essential for early detection and safe management.
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References
- ACOG Practice Bulletin No. 204: Fetal Growth Restriction (Reaffirmed 2024)
- RCOG Green-top Guideline No. 31, Updated May 2024
- WHO Technical Advisory Group Priorities: Maternal & Perinatal Health 2024–2025
- FIGO World Congress Highlights: IUGR Guidelines, 2025
- DGGG/OEGGG/SGGG Guideline on FGR, October 2024
- NHS North West Regional Guideline for Detection & Management of FGR, April 2025
- Journal of Maternal–Fetal & Neonatal Medicine, Clinical Practice Guidance for FGR, 2025
References are provided for educational transparency and do not replace clinical judgment.
Author Note
Dr Humaira Latif, Registered Medical Practitioner and Gynaecology & Obstetrics Specialist, with over 14 years of clinical and practical experience. This article was last updated on January 5, 2026, in accordance with current international guidelines.
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