WHO INTERGROWTH-21st Fetal Growth Standard Tables
Quick Take
INTERGROWTH-21st is WHO's global fetal growth standard. It provides 5th-95th percentiles for fetal weight, length, head circumference, and abdominal circumference from 22 to 40 weeks. Multi-ethnic data from 19 countries. SGA = <10th percentile. LGA = >90th percentile. Mean weight at 40 weeks = 3300g (7.3 lbs). Head circumference increases 1.2cm/week in third trimester. Abdominal circumference increases 0.8cm/week. Use the [Fetal Growth Percentile Calculator] to assess your baby's growth.
The INTERGROWTH-21st Project is an international collaboration led by the World Health Organization (WHO) to establish global fetal growth standards. These standards provide evidence-based reference values for assessing fetal development across diverse populations.
Want to assess your baby's growth? Use the [Fetal Growth Percentile Calculator] to determine percentile rankings.
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INTERGROWTH-21st Overview
The INTERGROWTH-21st Project began in 2008 and published its final results in 2014.
Study Design
- Population-based prospective cohort study
- 19 countries across 6 continents
- 13,871 pregnant women enrolled
- 8,200 singleton live births analyzed
- Strict inclusion criteria: no maternal complications
- Serial ultrasound measurements from 14 weeks
Key Objectives
- Establish global fetal growth standards
- Develop international reference curves
- Provide tools for prenatal screening
- Improve perinatal outcomes worldwide
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Fetal Weight Percentiles
The INTERGROWTH-21st weight standards provide percentiles from 22 to 40 weeks.
| Gestational Age (weeks) | 5th Percentile (lbs) | 10th Percentile (lbs) | 50th Percentile (lbs) | 90th Percentile (lbs) | 95th Percentile (lbs) |
|---|---|---|---|---|---|
| 22 | 0.7 (320g) | 0.8 (360g) | 1.0 (460g) | 1.3 (570g) | 1.4 (620g) |
| 24 | 1.0 (460g) | 1.1 (520g) | 1.5 (660g) | 1.8 (820g) | 2.0 (900g) |
| 26 | 1.4 (640g) | 1.6 (720g) | 2.0 (920g) | 2.5 (1140g) | 2.8 (1250g) |
| 28 | 1.9 (880g) | 2.2 (980g) | 2.8 (1250g) | 3.4 (1550g) | 3.7 (1690g) |
| 30 | 2.6 (1170g) | 2.9 (1300g) | 3.6 (1650g) | 4.5 (2050g) | 4.9 (2230g) |
| 32 | 3.3 (1500g) | 3.7 (1660g) | 4.6 (2100g) | 5.7 (2600g) | 6.2 (2820g) |
| 34 | 4.1 (1870g) | 4.5 (2060g) | 5.7 (2600g) | 7.1 (3200g) | 7.6 (3470g) |
| 36 | 5.0 (2270g) | 5.5 (2490g) | 6.8 (3100g) | 8.4 (3800g) | 9.1 (4110g) |
| 38 | 5.8 (2650g) | 6.4 (2900g) | 7.9 (3580g) | 9.6 (4350g) | 10.4 (4700g) |
| 40 | 6.5 (2970g) | 7.2 (3250g) | 8.8 (3990g) | 10.6 (4800g) | 11.4 (5180g) |
Head Circumference Standards
| Gestational Age (weeks) | 5th Percentile (inch) | 10th Percentile (inch) | 50th Percentile (inch) | 90th Percentile (inch) | 95th Percentile (inch) |
|---|---|---|---|---|---|
| 22 | 6.1 (15.5cm) | 6.3 (16.0cm) | 6.9 (17.5cm) | 7.5 (19.0cm) | 7.7 (19.6cm) |
| 24 | 6.9 (17.5cm) | 7.1 (18.1cm) | 7.8 (19.8cm) | 8.5 (21.6cm) | 8.8 (22.3cm) |
| 28 | 8.5 (21.5cm) | 8.7 (22.2cm) | 9.5 (24.2cm) | 10.4 (26.4cm) | 10.7 (27.2cm) |
| 32 | 9.8 (25.0cm) | 10.2 (25.8cm) | 11.1 (28.1cm) | 12.0 (30.5cm) | 12.4 (31.4cm) |
| 36 | 11.0 (28.0cm) | 11.4 (28.9cm) | 12.4 (31.4cm) | 13.4 (34.1cm) | 13.8 (35.1cm) |
| 40 | 12.0 (30.5cm) | 12.4 (31.5cm) | 13.5 (34.2cm) | 14.6 (37.1cm) | 15.0 (38.2cm) |
Abdominal Circumference Standards
| Gestational Age (weeks) | 5th Percentile (inch) | 10th Percentile (inch) | 50th Percentile (inch) | 90th Percentile (inch) | 95th Percentile (inch) |
|---|---|---|---|---|---|
| 22 | 4.7 (12.0cm) | 5.0 (12.6cm) | 5.7 (14.4cm) | 6.5 (16.4cm) | 6.8 (17.2cm) |
| 24 | 5.5 (14.0cm) | 5.8 (14.7cm) | 6.6 (16.8cm) | 7.5 (19.1cm) | 7.9 (20.1cm) |
| 28 | 7.0 (17.8cm) | 7.4 (18.7cm) | 8.3 (21.2cm) | 9.5 (24.1cm) | 10.0 (25.3cm) |
| 32 | 8.3 (21.2cm) | 8.7 (22.2cm) | 9.9 (25.2cm) | 11.2 (28.5cm) | 11.8 (29.9cm) |
| 36 | 9.5 (24.2cm) | 10.0 (25.3cm) | 11.3 (28.7cm) | 12.8 (32.4cm) | 13.4 (34.0cm) |
| 40 | 10.5 (26.8cm) | 11.0 (28.0cm) | 12.5 (31.8cm) | 14.2 (36.0cm) | 14.8 (37.7cm) |
Femur Length Standards
| Gestational Age (weeks) | 5th Percentile (inch) | 10th Percentile (inch) | 50th Percentile (inch) | 90th Percentile (inch) | 95th Percentile (inch) |
|---|---|---|---|---|---|
| 22 | 1.1 (2.7cm) | 1.1 (2.9cm) | 1.3 (3.4cm) | 1.6 (4.0cm) | 1.7 (4.3cm) |
| 24 | 1.3 (3.3cm) | 1.4 (3.5cm) | 1.6 (4.1cm) | 1.9 (4.8cm) | 2.0 (5.1cm) |
| 28 | 1.7 (4.4cm) | 1.9 (4.7cm) | 2.2 (5.5cm) | 2.5 (6.4cm) | 2.7 (6.8cm) |
| 32 | 2.2 (5.5cm) | 2.3 (5.8cm) | 2.7 (6.8cm) | 3.1 (7.9cm) | 3.3 (8.4cm) |
| 36 | 2.5 (6.4cm) | 2.7 (6.8cm) | 3.1 (7.9cm) | 3.6 (9.1cm) | 3.8 (9.6cm) |
| 40 | 2.8 (7.2cm) | 3.0 (7.6cm) | 3.5 (8.8cm) | 4.0 (10.1cm) | 4.2 (10.7cm) |
Fetal Growth Velocity
Growth velocity provides insight into fetal well-being.
| Measurement | Growth Velocity (30-40 weeks) | Range | Clinical Significance |
|---|---|---|---|
| Weight | ~0.55 lb/week (250 g/week) | 0.33-0.77 lb/week (150-350 g/week) | Slower velocity may indicate IUGR |
| Head Circumference | ~0.5 inch/week (1.2 cm/week) | 0.3-0.6 inch/week (0.8-1.5 cm/week) | Abnormal velocity may indicate neurological issues |
| Abdominal Circumference | ~0.3 inch/week (0.8 cm/week) | 0.2-0.4 inch/week (0.5-1.1 cm/week) | Slower velocity may indicate placental insufficiency |
| Femur Length | ~0.3 inch/week (0.7 cm/week) | 0.2-0.4 inch/week (0.5-0.9 cm/week) | Reflects skeletal growth |
Growth Classification
| Classification | Percentile Range | Incidence | Clinical Implications |
|---|---|---|---|
| Small for Gestational Age (SGA) | <10th | ~10% | Increased perinatal mortality, preterm delivery |
| Appropriate for Gestational Age (AGA) | 10th-90th | ~80% | Normal growth, low risk |
| Large for Gestational Age (LGA) | >90th | ~10% | Increased shoulder dystocia, birth injury, cesarean |
Clinical Application
| Application | Usage | Threshold | Action |
|---|---|---|---|
| Screening for IUGR | Serial ultrasound measurements | Weight <3rd percentile or growth velocity <5th percentile | Refer for specialist care |
| Macrosomia Risk | Estimated fetal weight >4000g | >90th percentile | Consider induction or cesarean |
| Gestational Age Assessment | Biometric measurements | Multiple parameters | Determine due date |
| Surveillance | Third trimester growth scans | Every 3-4 weeks for high-risk | Monitor growth trajectory |
Comparison with Other Standards
| Standard | Data Source | Strengths | Limitations |
|---|---|---|---|
| INTERGROWTH-21st | Multi-ethnic, 19 countries | Global applicability, WHO-endorsed | Resource-intensive implementation |
| Hadlock Formula | US population | Widely used, simple | Ethnically homogeneous |
| ACOG Guidelines | US clinical data | Evidence-based | US-centric |
| Customized Growth Charts | Individualized | Account for maternal factors | Complex calculation |
Data Source Citations
Data Source
Last Updated
Author / Issuing Body
Reference Links
ACOG Practice Bulletin on Fetal Growth
2020
American College of Obstetricians and Gynecologists
Frequently Asked Questions
INTERGROWTH-21st is an international fetal growth standard developed by WHO, providing reference percentiles (5th-95th) for fetal weight, length, head circumference, and abdominal circumference from 22 to 40 weeks of gestation. Data was collected from 19 countries across 6 continents.
SGA is defined as fetal weight or biometric measurements below the 10th percentile for gestational age. Approximately 10% of pregnancies are classified as SGA, but only 25-30% are pathologically growth restricted.
LGA is defined as fetal weight or biometric measurements above the 90th percentile for gestational age. LGA infants have increased risk of shoulder dystocia, birth injury, and cesarean delivery.
According to INTERGROWTH-21st standards, the mean fetal weight at 40 weeks is approximately 3990g (8.8 lbs). The 10th percentile is 3250g (7.2 lbs) and the 90th percentile is 4800g (10.6 lbs).
Fetal growth accelerates in the third trimester: weight increases ~250g/week, head circumference ~1.2cm/week, abdominal circumference ~0.8cm/week, and length ~0.7cm/week from 30-40 weeks.
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Disclaimer: All calculations and data on this website are for informational reference only. This tool does not provide medical advice, diagnosis, or treatment. For health-related concerns, please consult a qualified healthcare professional.