Under 35
35 – 37
38 – 40
41 – 42
Over 42
Egg Donor
Adjust Attrition Rates (Advanced) ▼
Adjust these percentages based on your clinic's averages or personal history.
%
%
%
%
Estimated Funnel Results
1. Eggs Retrieved
Starting Count
0
2. Mature Eggs (MII)
Ready for fertilization
0
3. Fertilized (2PN)
Successfully fertilized
0
4. Blastocysts
Day 5/6 Embryos
0
5. Euploid Embryos
Chromosomally Normal (PGT-A)
0
Total Attrition from Retrieval to Euploid:
0%
*Estimates only. Individual results vary significantly.
function toggleAdvanced() {
var advDiv = document.getElementById('advanced-settings');
var toggleText = document.querySelector('.toggle-advanced');
if (advDiv.style.display === 'block') {
advDiv.style.display = 'none';
toggleText.innerHTML = 'Adjust Attrition Rates (Advanced) ▼';
} else {
advDiv.style.display = 'block';
toggleText.innerHTML = 'Hide Advanced Settings ▲';
}
}
function updateEuploidyDefaults() {
var age = document.getElementById('patientAge').value;
var euploidyInput = document.getElementById('euploidyRate');
// Approximate euploidy rates based on age stats (generic medical averages)
var rate = 60; // Default under 35
if (age === '35-37′) rate = 50;
else if (age === '38-40′) rate = 35;
else if (age === '41-42′) rate = 20;
else if (age === 'over42') rate = 10;
else if (age === 'donor') rate = 70; // Young donor eggs
euploidyInput.value = rate;
}
function calculateAttrition() {
// Clear errors
document.getElementById('error-message').innerHTML = "";
// Get Inputs
var eggsStart = parseFloat(document.getElementById('eggsRetrieved').value);
var matRate = parseFloat(document.getElementById('maturityRate').value) / 100;
var fertRate = parseFloat(document.getElementById('fertilizationRate').value) / 100;
var blastRate = parseFloat(document.getElementById('blastocystRate').value) / 100;
var euploidRate = parseFloat(document.getElementById('euploidyRate').value) / 100;
// Validation
if (isNaN(eggsStart) || eggsStart eggsStart) matureCount = eggsStart;
// Calculate Step Attrition (Loss %)
// Attrition = (Previous – Current) / Previous
function calcLoss(prev, curr) {
if (prev === 0) return "100%";
var loss = ((prev – curr) / prev) * 100;
return "-" + Math.round(loss) + "% Loss";
}
// Display Results
document.getElementById('res-eggs').innerText = eggsStart;
document.getElementById('res-mature').innerText = matureCount;
document.getElementById('att-mature').innerText = calcLoss(eggsStart, matureCount);
document.getElementById('res-fert').innerText = fertCount;
document.getElementById('att-fert').innerText = calcLoss(matureCount, fertCount);
document.getElementById('res-blast').innerText = blastCount;
document.getElementById('att-blast').innerText = calcLoss(fertCount, blastCount);
document.getElementById('res-euploid').innerText = euploidCount;
document.getElementById('att-euploid').innerText = calcLoss(blastCount, euploidCount);
// Total Attrition
var totalLoss = ((eggsStart – euploidCount) / eggsStart) * 100;
document.getElementById('total-attrition').innerText = Math.round(totalLoss) + "% Drop-off";
// Show Area
document.getElementById('result-area').style.display = 'block';
}
Understanding the Embryo Attrition Funnel
In Vitro Fertilization (IVF) involves a series of biological hurdles, often referred to as the "IVF Funnel." It is statistically normal for the number of viable embryos to decrease at every stage of the process, from egg retrieval to the final genetic testing.
What is Embryo Attrition?
Embryo attrition refers to the natural reduction in the number of developing embryos as they progress through the laboratory culture stages. This calculator helps patients set realistic expectations by estimating the drop-off rate based on standard medical benchmarks and age-related statistics.
The 4 Stages of the Funnel
Maturity (MII): Not all eggs retrieved are mature. Only mature eggs (Metaphase II) can be fertilized. Typically, 80% of retrieved eggs are mature.
Fertilization: This occurs when sperm enters the egg. Standard fertilization rates (via IVF or ICSI) hover around 70-80% of mature eggs.
Blastocyst Formation: This is often the steepest drop-off. A fertilized egg must divide and grow to Day 5 or Day 6 to become a blastocyst. On average, only 30-50% of fertilized eggs reach this stage.
Euploidy (PGT-A): If genetic testing is performed, embryos are checked for the correct number of chromosomes. This rate is heavily dependent on egg age. For women under 35, roughly 50-60% of blastocysts are normal (euploid). For women over 40, this rate drops significantly.
Why Do the Numbers Drop?
Attrtion is a biological quality control mechanism. Embryos that stop developing usually have chromosomal abnormalities or insufficient energy to continue dividing. While seeing the numbers drop can be emotionally difficult, it is a normal part of the process that occurs in both natural conception and IVF.
Note: This calculator provides estimates based on statistical averages. Individual results depend on specific diagnosis, clinic protocols, and gamete quality.