Decode an IVF success rate denominator
Work out whether a clinic number is per cycle started, per transfer, or something else, then ask a sharper question.
What kind of success number were you shown?
Pick the closest match to the clinic headline or brochure.
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IVF success denominators
A percent is unfinished until you know what sits under the line. Per cycle started, per egg collection, per embryo transferred, per pregnancy, and cumulative from one stimulation are different jobs. Donor eggs and frozen transfers are different again.
Clinical pregnancy versus live birth
A scan heartbeat is not a live birth. SET versus DET changes twin risk more than it changes the meaning of a denominator. Age mix inside a clinic table can hide a steep drop after 40. Read IVF single embryo transfer and fertility odds by age.
Add on marketing
PGT, assisted hatching, and time lapse can change who reaches transfer. That can lift a per transfer number without lifting live birth per started cycle. Ask whether cancelled cycles are in the figure, and which year the registry used.
Name the registry and the year
Ask which registry and year a number comes from. HFEA covers the UK. CDC SART covers the US. ANZARD covers Australia and New Zealand. CARTR Plus covers Canada. Mixing those tables into one fake rate hides age mix, donor eggs, and cancelled cycles.
One embryo versus two
Single embryo transfer changes twin risk more than it changes what a denominator means. Age mix inside a clinic table can hide a steep drop after 40. Read IVF single embryo transfer.
Testing after transfer
After a transfer you will want a home test. An hCG trigger can still paint a line. See when to take a pregnancy test and signs after embryo transfer. Photograph the pregnancy test after transfer and get a line reading in seconds.
Frequently Asked Questions
What is the difference between per transfer and per cycle started?
Per embryo transferred only counts people who had an embryo placed. Per cycle started includes people who cancelled, had no eggs, or had no embryo. The per transfer number often looks 20 to 40 points higher.
Is clinical pregnancy the same as live birth?
No. Clinical pregnancy can mean a scan finding. Live birth is a baby born. Miscarriage sits between those two, so live birth is lower.
Do donor egg rates apply to my age?
Usually not. Donor egg tables follow the donor age more than the recipient age. Mixing those tables with own egg rates is a common brochure trick.
Which registry should a UK clinic name?
Ask for HFEA and the year. In the US ask for CDC SART. In Australia or New Zealand ask for ANZARD. In Canada ask for CARTR Plus.
When should I test after a transfer?
Follow the clinic blood test date when you can. Home tests can turn positive from an hCG trigger shot. Scan the strip, and read when to take a pregnancy test after treatment.
