How to Read IVF Success Rates and Why the Number Isn’t the Whole Story

If you’ve started researching IVF success rates, you’ve probably run into numbers that don’t seem to add up: a clinic’s website might advertise a 60% success rate, while their official SART report for the same year shows something closer to 40%. But neither number is wrong – they’re simply answering different questions.

Before going further, a few terms are worth defining. In vitro fertilization (IVF) is the process of retrieving eggs, fertilizing them in a lab, and transferring an embryo back into the uterus. You’ll also see the Society for Assisted Reproductive Technology (SART) and Assisted Reproductive Technology (ART) throughout this guide, along with frozen embryo transfer (FET) and preimplantation genetic testing (PGT), a lab process used to screen embryos before transfer.

By the end of this article, you’ll be able to read your own clinic’s data with confidence and understand that a percentage is only one part of what success looks like during treatment.

What Are IVF Success Rates Actually Measuring?

A success rate probably sounds like one thing to you: the chance of having a baby. But clinics and databases actually track three different milestones on the way to that outcome, and each one becomes its own rate: a pregnancy test rate, a clinical pregnancy rate, and a live birth rate, all calculated from the exact same group of people who started treatment:

• The pregnancy test rate only counts those who had a hormone level come back elevated.
• The clinical pregnancy rate only counts those who had a heartbeat confirmed on ultrasound, usually a few weeks later.
• The live birth rate only counts those who actually had a baby, and it’s the only one of the three that guarantees someone left treatment with a child.

Many pregnancies that reach a confirmed heartbeat go on to result in a live birth. For people whose pregnancies reach a confirmed heartbeat but don’t go on to a live birth, that gap between milestones is exactly why a clinic’s pregnancy test rate will almost always run higher than its live birth rate, even though both numbers come from the same starting group of people.

Two organizations track this data nationally. SART, the Society for Assisted Reproductive Technology, collects reports directly from its member clinics every year, and the CDC independently verifies and publishes that same data.

Some clinics also set their own criteria for who they’ll treat before a cycle ever begins, such as a minimum anti-Mullerian hormone (AMH) level, a maximum follicle-stimulating hormone (FSH) level, or an age cutoff. A clinic with stricter intake criteria will naturally show a higher success rate, simply because it’s treating a narrower, more likely-to-succeed group of people. Those criteria matter just as much as the published percentage once you start comparing clinics directly.

Live Birth Rate vs. Pregnancy Rate: Why It Matters

The IVF live birth rate per intended retrieval is the number worth looking for when you’re comparing clinics. It counts everyone who started a cycle, whether or not they later reached a positive test or a confirmed heartbeat. 

A rate built on an earlier milestone will almost always look higher, simply because fewer people have had the chance to experience a loss by that point.

Why You Can’t Compare Clinics Side by Side

Understanding IVF success rate by clinic data starts with knowing why raw numbers alone can mislead you. SART and CDC both state that comparing clinics directly isn’t scientifically valid, and the reason comes down to who each clinic treats. A clinic that accepts people at higher ages, with more complex diagnoses, or after multiple unsuccessful treatments elsewhere will show a lower raw rate than a clinic that limits who it accepts, even if both clinics provide equally excellent care. 

FINO, for instance, is known for taking on complex cases that other clinics have turned away, which is part of why comparing raw numbers alone doesn’t tell the full story.

That raw number also can’t tell you what treatment would feel like at a given clinic. Two clinics with success rates a percentage point or two apart can offer very different levels of communication and support along the way, and none of that appears in a SART report. When success rates are that close, many people weigh the difference in care just as heavily as the statistic itself.

Chasing the highest published number can also steer you toward a clinic that simply excludes more complex cases, rather than one that provides better care. Comparing raw rates without asking what population they represent tells you very little about your own likely outcome.

A comparison of clinic success rates may not be personally applicable because patient medical characteristics, treatment approaches, and entry criteria for ART may vary from clinic to clinic.

What Clinic Selection Practices Can Inflate Numbers

Some clinics discourage people with a lower prognosis from starting treatment there, or steer them toward donor egg cycles, which tend to post higher success rates. Neither practice is universal, and it doesn’t mean any single clinic is acting in bad faith. It’s worth asking your own care team directly how they approach patient evaluation and selection, and what criteria they use, before you start treatment.

How Age Affects the Data and Why It’s the Most Important Variable

Age at egg retrieval is the single strongest predictor of IVF outcome, a factor CDC’s national ART data confirms across clinics nationwide. FINO’s own guidance on who’s a good candidate for IVF reflects the same pattern, since age thresholds are part of how the clinic evaluates candidacy in the first place. Here is FINO’s 2023 SART data, broken down by age bracket at retrieval:

• Under 35: this age group showed a 48.8% live birth rate across 127 cycles.
• 35 to 37: this age group showed a 45.5% live birth rate across 66 cycles.
• 38 to 40: this age group showed a 29.6% live birth rate across 54 cycles.
• 41 to 42: this age group showed a 20.7% live birth rate across 29 cycles.
• Over 42: this age group showed a 15.4% live birth rate across 13 cycles.

This kind of IVF success rate by age breakdown is exactly what you’ll find on any clinic’s SART profile. It’s meant to show how outcomes trend across a broad population, rather than predict what will happen for you individually.

Age brackets are also based on age at retrieval rather than age at transfer. If you froze eggs years ago and are returning for a transfer now, the age bracket reflects how old you were at that original retrieval.

Own Eggs vs. Donor Eggs: Separate Data Sets

Success rates for cycles using your own eggs and cycles using donor eggs are reported separately and should never be averaged together. Donor egg cycles typically show higher success rates because the donor’s age, rather than yours, is the variable driving the outcome.

Neither path is better than the other. They’re simply different data sets shaped by different biology.

Understanding How Cycles Are Counted

IVF statistics depend heavily on which denominator a clinic uses. A success rate is really just live births divided by that denominator, and clinics can calculate it using intended retrievals, actual retrievals, or embryo transfers. The same clinic can report very different-looking numbers depending on which one it chooses.

Live births per intended retrieval is generally the most complete version, since it includes everyone who started a cycle, even the people who didn’t make it to retrieval or transfer at all.

Cumulative success rates count every live birth that comes from a single egg retrieval, including any frozen embryo transfers that used embryos from that same batch, while single-cycle rates count only the one transfer being reported. 

Because cumulative rates reflect the full outcome of a retrieval rather than a single attempt, they tend to run higher.

Fresh vs. Frozen Embryo Transfer Success Rates

Frozen embryo transfer (FET) success rates are now comparable to, or in some cases higher than, fresh transfer rates at many clinics. Much of that change comes from giving the uterus time to recover from ovarian stimulation before a frozen transfer takes place. 

Whether fresh or frozen transfer makes more sense for you depends on your specific situation, which is best discussed directly with your care team.

How to Find and Read FINO’s SART Profile

You can look up fertility clinic success rates for any provider directly at sartcorsonline.com by searching for the clinic’s name or zip code. Once you find the report, you’ll see outcome data broken down by age bracket, along with the number of cycles and live births per intended retrieval for each group. The column headers can look intimidating at first, but they follow the exact structure explained throughout this guide.

FINO’s own success rate data, including the 2023 figures referenced earlier, is available on FINO’s SART Clinic Summary Report. Bringing that data to your first consultation, rather than trying to interpret it alone, gives your care team the chance to put the numbers in context for your specific situation.

A number on a page can’t predict your individual outcome, but a conversation with a specialist can help you understand what it actually means for you.

Your Data Questions Deserve Real Answers

You now have a framework for reading SART and CDC data, from live birth rates to age brackets to how cycles get counted. But a percentage on a page is only one part of the picture, since how supported you feel throughout treatment matters just as much as any number attached to it because you are not a number or a statistic.

The next step is a conversation with a specialist who can walk through your own numbers honestly, without pressure or guarantees. Request an appointment at FINO to start that conversation today.