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A calculator sees three or four figures. A specialist sees your history, your scans, your partner's results, and how you actually responded to treatment. If you're between cycles, changing clinics, or something in your results doesn't add up, a second opinion is the fastest way to find out whether anything would be done differently.

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These tools provide general information and are not a diagnosis or a substitute for assessment by a qualified clinician. Reference ranges and sources are stated on each calculator. Predictive estimates describe groups of people and cannot predict an individual outcome.

Other categories

Second opinion

Bring your numbers to someone who can see the rest

A calculator sees three or four figures. A specialist sees your history, your scans, your partner's results, and how you actually responded to treatment. If you're between cycles, changing clinics, or something in your results doesn't add up, a second opinion is the fastest way to find out whether anything would be done differently.

Free first consultation. No obligation to start treatment, and it doesn't affect your care at your current clinic.

‹ Embryology

Embryo attrition

The whole funnel — eggs to mature to fertilised to blastocyst to euploid.

Exact calculationArithmetic on the numbers you enter. If your inputs are right, this figure is right.

inputEggs retrievedinputMature (MII)inputFertilised (2PN)inputBlastocysts=resultEmbryo attrition funnel (%)
In short

The attrition funnel tracks eggs retrieved through mature, fertilised, and blastocyst stages. Where a cycle dropped off is more informative than the final number: low maturity points at trigger timing, low fertilisation at sperm or method, low blastocyst conversion at egg quality.

Source — Attrition at each step varies with age and between laboratories. The step rates above are more informative than the overall figure.

Enter your values
25%

That falls in the 15–30% band.

Retrieved → mature83%
Mature → fertilised70%
Fertilised → blastocyst43%
Overall: eggs → blastocyst25%

Where this sits

Your result of 25 % sits in the highlighted band. Bands are reference points used alongside clinical findings — not a diagnosis.

<15%15–30%30%+
Expected Borderline Below expected Worth discussing
15–30% %

Within the range commonly reported across mixed populations.

Attrition at each step varies with age and between laboratories. The step rates above are more informative than the overall figure.

Where this sits in the process
Planning
Testing
Cycle
Stimulation
Laboratory
After transfer

Highlighted is the stage this measurement belongs to. It is a map of the process, not a schedule — timings vary by protocol and by clinic.

Questions this usually raises

Which step matters most?

The one where your numbers fall furthest below your unit’s typical rate. Low maturity points at trigger timing; low fertilisation at sperm or method; low blastocyst conversion at egg quality.

Is uniform loss at every step normal?

Some loss at every step is expected. Uniform heavy loss usually reflects egg quality, which tracks age and is not something anyone caused.

Which step should I ask about first?

The one furthest below your unit's typical rate for your age. If every step is roughly normal and the final number is simply small, the limiting factor was how many eggs you started with — a different conversation from one where a specific step failed.

Or ask someone
  • A free first consultation covers this properly, with your actual results rather than an estimate
  • Both partners assessed together — male factor is involved in roughly half of cases

Related calculators

Second opinion

Bring your embryo attrition result to someone who can see the rest

A calculator sees three or four figures. A specialist sees your history, your scans, your partner's results, and how you actually responded to treatment. If you're between cycles, changing clinics, or something in your results doesn't add up, a second opinion is the fastest way to find out whether anything would be done differently.

Free first consultation. No obligation to start treatment, and it doesn't affect your care at your current clinic.

Get a second opinion › Message us on WhatsApp

Compare each step against your own unit’s figures for your age band. Nothing here is a diagnosis or a substitute for assessment by a clinician.

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