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Fetal Weight Chart by Gestational Age
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A fetal weight reference tool based on NICHD Asian singleton data, helping expectant parents quickly assess their baby's growth.
This is a locally maintained static reference table, not a live official directory, current policy or complete collection. Records without a named source and update date remain unverified.
INTERGROWTH-21st 2020 Hadlock EFW equations: exact weeks 18–40, rounded grams, P3/P50/P97. International reference distribution, not individual weight prediction or a universal normal range. Reference
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
This reference table shows estimated fetal weight (EFW) values in grams for exact weeks from 18+0 through 40+0. Each row has the 3rd (P3), 50th (P50), and 97th (P97) centiles. For example, at 28+0 weeks the displayed values are 823 g, 1,022 g, and 1,271 g. These are positions in a reference distribution for that gestational age, not three diagnostic categories or a prediction of one fetus’s weight.
EFW is an estimate derived from ultrasound measurements. This page is a lookup table: it does not ask for head or abdominal measurements, calculate a new EFW, or turn a weight into an individual percentile. Its figures follow the INTERGROWTH-21st 2020 Hadlock estimated-weight reference. Values are shown as whole grams, so small differences can arise when comparing rounded figures with a report or another display.
A percentile describes a position within a reference distribution at a specified gestational age. P50 is the median: half of the reference values are below it and half above it. P3 and P97 mark the lower and upper tails of that distribution. They do not mean a 3%, 50%, or 97% chance that an individual fetus is healthy, and the table does not label a result normal or abnormal.
Centiles depend on the reference chart and the method used to estimate fetal weight. Different charts can assign different percentiles to the same reported weight. The INTERGROWTH-21st label identifies which reference this table represents; it does not make the values a universal national clinical standard.
The source is the INTERGROWTH-21st 2020 standard for Hadlock estimated fetal weight. The published work provides equations for estimated-weight centiles by gestational age; this table presents P3, P50, and P97 at whole-week points and rounds the gram values to integers.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Use the estimated fetal weight and unit from the ultrasound report. A head circumference, abdominal circumference, or birth weight is a different measurement and should not be read as EFW.
Choose the row for the exact completed week. The table samples week + 0 days only; it does not interpolate by day. A report at 28 weeks and 4 days is not an exact match for the 28+0 row.
Read across P3, P50, and P97 to see the reference values in grams. If the reported value falls between two columns, the table does not calculate its precise percentile. Bring the report’s own percentile and chart name to the clinician who interprets the scan.
The page’s search control can narrow the rows, and column headings can sort the table. For example, searching for 28 can bring the 28-week row into view. At 28+0 the figures are 823 g, 1,022 g, and 1,271 g; these are useful for identifying the row and chart, not for assigning a diagnosis.
Use cases
See how the tool fits into real work and everyday tasks.
An expectant parent can locate the correct whole-week row, note how centiles are labeled, and ask the care team which chart and EFW method appear in the report.
A student or editor can compare the three displayed centile columns for a specific week and keep the units and reference name attached to the values.
When two reports show different percentiles for similar weights, use the chart name and gestational-age convention as prompts for a clinician discussion rather than treating either number as interchangeable.
Q&A
Find concise answers to common questions and confusing cases.
No. It is the table’s P50 reference value at 28+0 weeks. EFW is an ultrasound estimate, not a direct weighing, and the table does not measure an individual fetus.
The table has rows at exact weeks from 18+0 to 40+0 only. It does not provide daily values or interpolate between rows, so use the gestational age and interpretation shown on the scan report.
The report may use another reference chart, EFW method, or gestational-age convention. Check the chart named on the report and ask the clinician who reviewed the scan how to interpret the difference.
No. Three centile values do not define every percentile between them. This table does not accept a weight or calculate an individual percentile.
No. A reference-table comparison alone is not a diagnosis. A qualified maternity clinician considers the complete scan, pregnancy dating, and relevant clinical information.
Notes
Review scope, result limitations, and important precautions before use.
This is general reference information, not medical advice, diagnosis, or a substitute for prenatal care. The figures describe an international reference distribution and are not a universal normal range or a personalized forecast. Do not change care or draw a conclusion about fetal health from one row or one estimated weight.
Only exact weeks from 18+0 through 40+0 are shown. Multiple gestations, a different gestational age, a report using another chart, or values outside this table require interpretation using the appropriate clinical reference. Discuss scan findings and any concern with a qualified obstetric clinician.
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