What does a fertility clinic’s success rate actually mean?
A fertility clinic’s published success rate is not a prediction for any one patient. It’s an average built from a specific group of patients, counted in a specific way. Two clinics can report very different numbers simply because they treat different kinds of patients, not because one provides better care. Reading these numbers well means checking who was counted, what counted as an attempt, and what counted as a success.
Where does fertility clinic success rate data come from?
Clinics that perform assisted reproductive technology, or ART — procedures like in vitro fertilization (IVF) that involve handling eggs or embryos outside the body — report their cycle data to the Centers for Disease Control and Prevention (CDC) each year. The CDC’s ART Success Rates tool lets anyone look up a reporting clinic’s numbers by clinic, state, or nationally.
Reporting isn’t universal. The CDC estimates its published data represents roughly 97 to 98 percent of all ART cycles performed nationally, and clinics that don’t report tend to be smaller, lower-volume practices. That gap is small at the national level, but it’s a reminder that “all U.S. clinics” and “all reporting clinics” aren’t quite the same set.
How to read a clinic’s success rate data: an evidence ladder
Each clinic’s page on the CDC tool is organized into five tabs. Working through them in order, rather than jumping to the headline percentage, builds a far more accurate picture.
Step 1: Clinic Services and Profile
Shows what the clinic offers, its location, and its total cycle volume. A clinic performing a handful of cycles a year and one performing thousands aren’t directly comparable, even when their percentages look similar.
Step 2: Patient and Cycle Characteristics
This is the patient-mix tab. It shows the age distribution, diagnosis types, and treatment history of patients that specific clinic treats, with an option to compare against national data. A clinic treating more older patients or more complex diagnoses will tend to show lower success percentages for reasons unrelated to quality of care.
Step 3: Success Rates — Patients Using Their Own Eggs
Broken out by age group (currently under 35, 35–37, 38–40, and over 40) and by whether the patient was new to ART or had tried before. This is also where the denominator question, covered next, matters most.
Step 4: Success Rates — Patients Using Donor Eggs
Donor-egg cycles are reported separately and counted differently, so they shouldn’t be set beside own-egg numbers when comparing clinics.
Step 5: Clinic Data Summary
A combined snapshot of the previous four tabs, useful as a final check once you’ve read the detail behind it.
Why does the denominator change a clinic’s success rate?
A success rate is a fraction, and the denominator — what’s being counted as the pool of attempts — changes what the rate actually measures. For patients using their own eggs, the CDC reports cumulative success rates, which include embryo transfers happening within one year of a single egg retrieval, not just a first attempt. That differs from a noncumulative rate, which counts only one cycle or transfer on its own.
Donor-egg cycles are reported as noncumulative rates, based on donor cycles started in a given year regardless of when the donor eggs were originally retrieved. If you’re comparing a cumulative own-egg rate at one clinic to a noncumulative donor-egg rate at another, stop — the counting method itself likely explains most of the gap, not the clinics’ relative skill.
One more denominator detail: cycles where eggs or embryos were frozen for future use, with no transfer planned in that cycle, are handled separately in CDC reporting and aren’t counted the same way as cycles started with the intent to transfer an embryo.
What do we know — and not know — about fertility clinic success rates?
Well established:
- Clinic-level and national ART data are collected and verified annually, covering the large majority of U.S. ART cycles performed.
- Success rates vary meaningfully by patient age, diagnosis, and treatment history, according to the CDC.
- Own-egg rates are cumulative; donor-egg rates are noncumulative — these are not interchangeable numbers.
- To protect patient privacy, the CDC suppresses figures based on very small group sizes (counts of 1 to 4), so some breakdowns for a given clinic may not be shown at all.
What the data can’t tell you:
- How your own diagnosis, age, and health history will affect your personal odds — the CDC itself notes that average chances may not reflect an individual’s or couple’s actual chances.
- Why a clinic’s rate changed year to year without knowing whether its patient mix, reporting method, or age-band definitions changed too — the CDC’s own age categories have been redefined several times since 1995.
- Cost, wait times, communication style, or anything about the experience of being a patient there — none of that is captured in success rate data.
A checklist for comparing fertility clinic success rates
- Open the Patient and Cycle Characteristics tab before the success rate tab, and compare that clinic’s patient mix to the national average.
- Confirm whether you’re looking at a cumulative rate (own eggs) or a noncumulative rate (donor eggs) before comparing two clinics.
- Look at the age-group breakdown closest to your own age, not the clinic’s overall headline number.
- Check the total number of cycles the clinic performed — a rate built from very few patients is less stable than one built from a large group.
- If a breakdown you want is missing, it may be suppressed because the group was smaller than five patients; ask the clinic directly rather than assuming the hidden number was unfavorable.
- Write down your specific questions about denominators and patient mix before a consultation, so a clinician can walk through how the published numbers relate to your own situation.
When should I talk to a doctor instead of comparing more clinics?
Success rate data is a starting point for comparing clinics, not a substitute for a conversation with a qualified reproductive endocrinologist about your own diagnosis, age, and treatment options. If you’ve worked through the checklist above and still can’t tell how a clinic’s numbers apply to your situation, that conversation — not another spreadsheet — is the right next step. Our Medical Disclaimer has more on how to use educational content like this alongside professional care.
Frequently asked questions about fertility clinic success rates
Is a higher success rate always a better clinic?
Not necessarily. A clinic’s rate reflects both its clinical practice and the patients it treats. A clinic that takes on more complex cases, such as older patients or those with prior failed cycles elsewhere, will often show lower rates than a clinic that treats a narrower, lower-risk patient group.
What’s the difference between a pregnancy rate and a live birth rate?
A pregnancy is confirmed earlier in the process and doesn’t always result in a live birth. The CDC’s clinic success rate figures are based on live birth outcomes, which is a stricter and more clinically meaningful measure than a pregnancy-only figure.
Can I compare success rates between two clinics directly?
Only if you’re comparing the same type of rate (both cumulative own-egg, or both noncumulative donor-egg), the same age group, and similar patient volume. Comparing mismatched categories will make two similarly performing clinics look very different.
Why does CDC data lag behind the current year?
ART outcomes, including births, can occur the year after a cycle starts, so clinics need time to finalize and verify results before reporting. The CDC’s published data typically reflects the most recently completed reporting year, not the current calendar year.
This article is for general educational purposes only and is not medical advice, a diagnosis, or a treatment recommendation. It does not describe the services, outcomes, or patient population of any specific clinic. Consult a licensed healthcare provider to discuss your own fertility treatment options.
Source data: CDC ART Success Rates and CDC NASS Technical Notes.
By Reproductive Health Center Health Education Team. Reviewed and updated: September 2026. See our Editorial Policy for sourcing standards, or read more About Reproductive Health Center.