Growth Monitoring • 28–40 Weeks
Fetal Growth Scan — Biometry and Estimated Fetal Weight
Accurate fetal size and growth assessment using standardised biometric measurements — monitoring growth trajectory across the third trimester. Science City & Naranpura, Ahmedabad.
What Does a Fetal Growth Scan Assess?
A fetal growth scan measures the baby’s dimensions to assess growth trajectory and estimate fetal weight. Unlike the anomaly scan, which focuses on structural detail, growth scans track whether the baby is growing at the expected rate for its gestational age — and whether that rate is sustained between appointments.
Biometric measurements taken:
HC
Head Circumference
Brain growth assessment; plotted against gestational age
AC
Abdominal Circumference
Liver size and nutritional status — the most sensitive single measure for growth restriction
FL
Femur Length
Skeletal growth; helps detect skeletal dysplasias
BPD
Biparietal Diameter
Head width; used together with HC for brain assessment
EFW
Estimated Fetal Weight
Calculated from HC + AC + FL using the Hadlock formula; plotted on growth charts
Growth centile charts: Measurements are plotted against INTERGROWTH-21st or Hadlock growth charts. A baby consistently below the 10th centile (SGA — small for gestational age) or showing a drop across centile lines between scans (growth restriction pattern) requires further Doppler assessment to evaluate placental function.
Growth Scan Schedule — When and How Often?
| Timing | Purpose | Who Needs It |
|---|---|---|
| 28 weeks | Baseline third trimester assessment — establishes growth trajectory | All pregnancies (especially high-risk) |
| 32 weeks | Mid-third trimester growth velocity — check for late-onset growth restriction | All high-risk; optional in low-risk |
| 36 weeks | Pre-delivery assessment: EFW, presentation, liquor, placenta location | All pregnancies |
| Every 2–3 weeks | Monitoring confirmed or suspected growth restriction | Twins, diabetes, hypertension, prior SGA, FGR |
Note: Growth scans before 24 weeks are not recommended as routine — fetal size variation at this stage is not clinically predictive of growth restriction. Growth restriction is predominantly a second half of pregnancy phenomenon.
Understanding Fetal Growth Restriction (FGR)
Fetal Growth Restriction (FGR) — previously termed IUGR — is a condition where the fetus fails to reach its genetic growth potential, most commonly due to placental insufficiency. Early identification and monitoring prevents adverse outcomes.
| Type | Onset | Characteristics | Management |
|---|---|---|---|
| Early-onset FGR | <32 weeks | Often associated with severe placental disease; significant Doppler abnormalities; worse prognosis | Intensive monitoring; timing of delivery critical |
| Late-onset FGR | >32 weeks | More common; subtler Doppler changes; may be missed without serial scanning | Serial growth + Doppler scans; planned delivery |
Key indicators on growth scan:
- ✓AC or EFW below the 10th centile for gestational age
- ✓AC crossing centile lines downward between serial scans
- ✓Reduced or absent amniotic fluid (oligohydramnios)
- ✓Abnormal umbilical artery Doppler waveforms (next step after growth scan)
Growth Scanning at Balaji Horizon
- Precise biometric measurements: GE Voluson systems at both Science City and Naranpura provide the image quality required for accurate HC, AC, FL, and BPD measurements.
- INTERGROWTH-21st and Hadlock growth charts: Measurements are compared against internationally validated growth standards for accurate centile assessment.
- ISUOG-trained specialist: Dr. Mayank Chaudhary performs and interprets all growth assessments to international standards.
- Integrated Doppler assessment: When growth restriction is suspected, umbilical artery and MCA Doppler are performed in the same appointment — avoiding separate visits.
- High-risk obstetric integration: All significant findings feed directly into Dr. Priyadatt Patel’s high-risk obstetric management pathway for planning.
Frequently Asked Questions
- Is the estimated fetal weight accurate?EFW has an inherent margin of approximately ±15–20%. A single EFW is less clinically meaningful than a trend across serial scans. Growth velocity — the rate of change in AC and EFW between scans — is more important than a single measurement in isolation.
- My baby is measuring small. Should I be worried?Not necessarily. “Small” can mean constitutionally small (a normal variant for that baby’s genetic make-up) or growth restricted (placental insufficiency). Doppler assessment and growth velocity across serial scans clarify this distinction. Most babies measuring small are entirely healthy.
- How often do I need growth scans?In a low-risk pregnancy: typically at 28, 32, and 36 weeks. In high-risk pregnancies (twins, maternal diabetes, hypertension, prior SGA baby): every 2–3 weeks from 26 weeks, or as directed by your clinician based on findings.
- Can a growth scan detect a large baby (macrosomia)?Yes. EFW above the 90th centile (large for gestational age, LGA) — often associated with maternal diabetes — is identified on growth scan. Management depends on EFW trend, glycaemic control, and clinical context. Macrosomia has implications for mode of delivery planning.
- Does fetal position affect measurement accuracy?Suboptimal fetal positioning can make abdominal circumference (AC) measurement more difficult to obtain accurately. The sonographer will attempt multiple views and optimise measurements. If position is unfavourable, a short wait or repeat appointment may occasionally be required.
Book Your Fetal Growth Scan
Serial growth assessment is essential for high-risk pregnancies. Book your third trimester growth scan at Balaji Horizon to monitor your baby’s growth trajectory with precision.
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