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Dr Pixel 2.0Women's imaging diagnosis

PLATFORM FOR EDUCATION AND DECISION SUPPORT IN WOMEN'S IMAGING

Understand the flow

Fetal weight, percentile, and fetal growth restriction management

Fetal weight assessment follows three steps: estimate the weight (Hadlock formulas), compare that weight to a reference curve by gestational age (INTERGROWTH-21st percentiles), and, when weight is below expected, apply a specific management protocol (Figueiras & Gratacós) to differentiate constitutional SGA from FGR and define delivery timing.

Estimated fetal weight percentile (INTERGROWTH-21st)

Fetal growth classification by percentile

P3P10P90P97
FGR< P3
SGAP3–P10
AGAP10–P90
LGAP90–P97
Macrosomia≥ P97

Estimated fetal weight (Hadlock)

Combines abdominal circumference (AC) and femur length (FL), with optional BPD and HC, in log₁₀(EFW) equations validated for decades. Average error margin of ±10%.

Percentiles (INTERGROWTH-21st)

Compares the biometric measurement (or estimated weight) to the expected distribution for gestational age, returning Z-score and percentile, with automatic growth classification.

Fetal growth restriction — management

Figueiras & Gratacós protocol: differentiates constitutional SGA from FGR and, in FGR cases, classifies into stages I to IV, each with recommended monitoring and delivery timing.

Percentile classification alone does not define an FGR diagnosis — the definition depends on clinical and fetal Doppler correlation.

Common questions

Frequently asked questions about fetal weight and FGR

What is the difference between SGA and FGR?+
SGA (Small for Gestational Age) refers only to estimated fetal weight below the 10th percentile, which may represent constitutionally small fetuses. FGR (Fetal Growth Restriction) implies compromised growth, generally associated with abnormal Doppler findings or weight below the 3rd percentile — it is not defined by weight alone.
What is the error margin of estimated fetal weight from Hadlock formulas?+
Estimated fetal weight has an approximate error margin of ±10%. Hadlock formulas are the most widely used worldwide, but have limitations at the extremes of fetal weight (FGR and macrosomia).
What differentiates early-onset from late-onset FGR?+
Early-onset FGR occurs before 32 weeks; late-onset FGR occurs from 32 weeks onward and can occur even with weight above the 3rd percentile.
Which protocol guides fetal growth restriction management in this app?+
The Figueiras & Gratacós protocol, used to differentiate constitutional SGA from FGR and, when applicable, to classify FGR into stages 1 to 4, each with monitoring and delivery-timing recommendations.
What is INTERGROWTH-21st?+
INTERGROWTH-21st (International Growth Standards for the 21st Century) is an international project that established modern, global standards for fetal and neonatal growth, used in this app to compute the Z-score and percentile of biometric measurements and estimated fetal weight.