Why are there three different 'success rates'?
Because each one divides a different number by a different number. A success rate is a fraction. Until you know the numerator and the denominator, a percentage tells you nothing.
The three you will see quoted:
- Live birth rate per embryo transfer. Of all embryo transfers into a gestational carrier, how many led to a live birth? This is a clinical measure. It is reported by fertility clinics to SART and the CDC, and it depends mostly on the embryo.
- Live birth rate per journey. Of all intended parents who matched with a surrogate, how many brought a baby home, however many transfers or rematches it took? This is the number most parents care about. It depends on the embryos, the surrogate, and whether the journey holds together through setbacks.
- Match rate. Of all intended parents who signed with an agency, how many were matched with a surrogate? This is an agency process measure. It says nothing about pregnancies or births.
All three are legitimate. They answer different questions. The problem comes when one is quoted as if it were another, or when they are blended into a single figure with no definition.
| Metric | Numerator | Denominator | Who reports it | What it tells you | What it hides |
|---|---|---|---|---|---|
| Live birth rate per transfer | Live births | Embryo transfers into a gestational carrier | Clinics, to SART and the CDC | How likely one transfer is to succeed | How many transfers a family needed; embryo selection differences between clinics |
| Live birth rate per journey | Families who brought a baby home | Families who matched | Agencies, if they choose to | How likely a matched family is to finish with a baby | How long it took; how many families left before matching |
| Match rate | Families matched | Families who signed | Agencies | How reliably an agency finds surrogates | Whether any of those matches led to a birth |
| Blended "success rate" | Undefined | Undefined | Marketing | Nothing you can check | Everything above |
What does SART report for gestational carrier cycles?
SART, the Society for Assisted Reproductive Technology, collects outcome data from its member clinics and publishes it, including cycles that use a gestational carrier. The CDC publishes national assisted reproductive technology data from clinic reports as well.
These reports are useful for one thing: understanding how often an embryo transfer into a gestational carrier results in a live birth, broken down by factors such as the age of the person whose eggs were used. They are reported per transfer or per cycle, not per surrogacy journey.
[Insert the current SART gestational carrier live birth rate per transfer, with the report year and the age band, pulled directly from the current SART report.]
Two cautions when you read clinic data. First, clinics differ in which patients they treat and how they select embryos, so clinic-to-clinic comparisons need care. Second, a per-transfer number is not your chance of bringing a baby home. Many families need more than one transfer.
What drives per-transfer success: embryo quality, PGT-A, carrier screening
Three factors carry most of the weight in whether a single transfer succeeds.
Embryo quality. This is the largest single factor. Embryo quality is driven mainly by the age of the person whose eggs created the embryo at the time the eggs were retrieved. Embryos from younger eggs, including donor eggs, are more likely to be chromosomally normal. See embryo quality.
PGT-A. Preimplantation genetic testing for aneuploidy checks embryos for an abnormal number of chromosomes before transfer. Selecting a chromosomally normal (euploid) embryo raises the chance that a given transfer succeeds and lowers the chance of miscarriage from chromosomal causes. It does not create more viable embryos. If you have three embryos and one is euploid, PGT-A tells you which one to transfer first; it does not change how many you have. See PGT testing.
Carrier screening. A gestational carrier has already shown she can carry a healthy full-term pregnancy. Careful screening of her medical history makes it more likely her uterus and her health support implantation and a healthy pregnancy. At Private Label Surrogacy, I read every surrogate candidate's prenatal and delivery records myself and write a physician medical summary that goes to your fertility clinic. The clinic then does its own medical screening. Neither step guarantees a pregnancy. Both reduce avoidable risk.
The clinic's lab, the transfer technique and the medication protocol matter too. Those are your clinic's responsibility, and SART data by clinic is one way to look at them.
What drives per-journey success: rematch, repeated transfers, persistence
A journey succeeds when a family brings a baby home. Getting there often takes more than one transfer, and sometimes more than one surrogate.
Repeated transfers. If the first transfer does not lead to a pregnancy, a second transfer with another embryo is common. The pregnancy test comes 9 to 11 days after each transfer. Each additional transfer adds a medical cycle of 2 to 3 months, plus travel, monitoring and clinic fees, and the surrogate's transfer fee. See failed transfers and miscarriage.
Embryo supply. A family with several euploid embryos can try again without a new IVF cycle. A family with one embryo left may need to create more before the next transfer.
Keeping the match together. After a failed transfer, a surrogate and intended parents have to decide together whether to try again. That depends on trust, clear communication and support for the surrogate. A match that breaks down after a failed transfer adds months.
Rematch. Sometimes a surrogate cannot continue, for medical or personal reasons. A rematch with a new screened surrogate keeps the journey going. The PLS Assured tier ($62,500) includes priority matching, unlimited rematches and no new agency fee if the first surrogate does not succeed.
The agency's influence on per-journey success is indirect: the quality of surrogate screening, how well it coordinates with your clinic, and whether it keeps the match intact through a setback. That is where an agency earns its fee. It cannot change your embryos.
Why a match rate is not a success rate
A match rate measures how often an agency finds a surrogate for families who sign. It is an operations number. It can be very high at an agency whose matches often fail, if it matches quickly with candidates who have not been fully screened and later fail clinic clearance.
A high match rate is good to have. It is not evidence about births. If an agency quotes a high percentage, ask: "Is that the share of families matched, or the share who brought a baby home?"
How to read an agency's claimed rate
When an agency quotes a single high percentage, ask four questions:
- What is the numerator? Pregnancies, live births, or matches?
- What is the denominator? Transfers, matched families, or signed families? Are families who left the program counted?
- Over what period? Since founding, last year, or a selected window?
- Who calculated it? The agency itself, or a clinic reporting to SART?
A claim that cannot answer all four is not a statistic. It is a slogan. Claims of near-perfect success deserve particular care.
A made-up example shows how much the denominator matters. Suppose an agency signs 100 families in a year. Ninety are matched. Of those 90, 70 bring a baby home within two years; some of the rest are still trying, and some stopped. The same agency could truthfully say "90% match rate," "78% of matched families had a baby," or "70% of families who signed had a baby." It could also quote a per-transfer rate from its partner clinics that is different again. Each number is accurate. Only one of them answers your question.
Also ask what happens to families for whom the journey did not succeed. An agency that can describe how it handled failed transfers and rematches is telling you more than one that only quotes a rate.
What PLS publishes and why
Private Label Surrogacy publishes counts with definitions, not a blended percentage:
- Journeys since 2017: more than 100. Definition: intended-parent families matched with a PLS surrogate.
- Babies born since 2017: more than 60. Definition: live births from PLS journeys.
We do not publish a single success percentage because it would blend clinical factors we do not control (your embryos, your clinic's lab) with agency factors we do (surrogate screening, coordination, keeping the match together). A blended figure would hide the one thing you need to know: which of the two is driving your own odds.
What we can tell you is what we do on the agency side. Every surrogate's records are read by a physician. Every surrogate completes an independent psychological evaluation before her profile is shown. Nancy Block, RN, runs matching personally, and two case managers, both former surrogates, carry the active matches. And when a transfer fails, the people who help you decide what comes next have been through it.
For your clinical odds, ask your fertility clinic about your embryos. For the agency side, judge us on the criteria for choosing an agency.
Sources
- SART, Society for Assisted Reproductive Technology, national summary and clinic data on gestational carrier cycles. [Report year to be added.]
- CDC, Assisted Reproductive Technology (ART) surveillance data.
- ASRM, American Society for Reproductive Medicine, guidance on preimplantation genetic testing and gestational carriers.
- Private Label Surrogacy journey and birth counts since 2017.