Fetal Growth Velocity Calculator
Signed difference between independently clinically dated compatible scan EFWestimates per week. Not true observed fetal-growth velocity, linear growth forecast or proof healthy/unhealthy growth; estimation uncertainty compounds.
Description
Estimated fetal-growth velocity compares matched weight estimates over an actual scan interval.
Estimated fetal-growth velocity compares matched weight estimates over an actual scan interval.1
Differences can include estimation variability as well as biological growth.
When to use Fetal Growth Velocity Calculator
Use this tool to calculate or review the supplied observations under the stated rules. Establish the observation date, units, measurement context and independently applicable clinical reference or calibrated model.
How to use Fetal Growth Velocity Calculator and understand its results
- Establish the observation date, units, measurement context and independently applicable clinical reference or calibrated model.
- Enter previousIndependentlyEstimatedFetalWeightGrams, currentIndependentlyEstimatedFetalWeightGrams, previousScanDate, currentScanDate, using the field meanings and rules below, then run the tool.
- Read result.signedEstimatedWeightChangeGrams, result.conditionalEstimatedGrowthGramsPerWeek. Use the units and sign conventions below.
- Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| previousIndependentlyEstimatedFetalWeightGrams | Previous independently estimated fetal weight grams | number | Required |
| currentIndependentlyEstimatedFetalWeightGrams | Current independently estimated fetal weight grams | number | Required |
| previousScanDate | Previous scan date | string | Required |
| currentScanDate | Current scan date | string | Required |
Require positive previous/current estimated fetal weights. Parse valid Gregorian scan dates with strictly positive elapsed days. Return current-minus-previous grams and seven times that change divided by elapsed days; loss remains negative.
changeGrams=currentEstimate−previousEstimate; growthGramsPerWeek=7×changeGrams/elapsedDays Use the matching field units and the exact boundary, ordering and reference rules above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Structured result; its nested fields below contain the actual calculation or selected reference | object |
| result.signedEstimatedWeightChangeGrams | Signed Estimated Weight Change Grams; preserve the subtraction order and sign defined in the mechanics | number |
| result.conditionalEstimatedGrowthGramsPerWeek | Conditional Estimated Growth Grams Per Week | number |
{
"input": {
"previousIndependentlyEstimatedFetalWeightGrams": 1000,
"currentIndependentlyEstimatedFetalWeightGrams": 1200,
"previousScanDate": "2026-01-01",
"currentScanDate": "2026-01-15"
},
"output": {
"result": {
"signedEstimatedWeightChangeGrams": 200,
"conditionalEstimatedGrowthGramsPerWeek": 100
}
}
}Limitations and assumptions
Dating evidence, acquisition conditions and applicable clinical references remain independently established. The output describes supplied observations or a conditional model without diagnosing an outcome, choosing a dose or verifying clinical applicability.
Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Extremely large composite outputs are rejected.
Alternative or Complementary methods
For a related step, use Fetal Weight Percentile Calculator: Estimated fetal-weight percentiles depend on an adopted growth reference and scan context. For a complementary comparison, use Twin Weight Discordance Calculator: Twin weight discordance expresses the difference between two estimated weights relative to the larger estimate.
References
-
Fetal Growth Velocity Calculator — tool.io
Similar or alternative tools
- Fetal Weight Percentile Calculator
Estimated fetal-weight percentiles depend on an adopted growth reference and scan context.
- Twin Weight Discordance Calculator
Twin weight discordance expresses the difference between two estimated weights relative to the larger estimate.