IVF Success Rates Explained
We are proud to be SART members and, as such, are required to report our statistics to the CDC National Registry. We do so, and are quite proud of our statistics, but feel that patients and potential patients need to understand the complexities involved. Program statistics should only be a small part of the decision making process involved in selecting a program.
|2014 Clinical Pregnancy Rate/Transfer|
|Age Group||Donor Eggs||<35||35-37||38-40||41-42||>42|
|Clinical Pregnancy Rate/Transfer||87% |
|Average # Embryos Transferred||1.9||1.8||1.4||1.7||2.3||3.0|
|Cumulative 7 Year Success Rates (Through 2013)|
|Pregnancy Rate per Transfer||56%||50%||46%||21%||13%||n/a*|
|Live Birth / Cycle Start||40%||28%||22%||11%||4%||n/a*|
|Live Birth / Retrieval||43%||32%||26%||13%||5%||n/a*|
|Live Birth / Transfer||48%||39%||30%||15%||7%||76%|
*Some of the cycle numbers are missing for donor cycles because that information was not published by SART
**Please note that a comparison of clinic success rates may not be meaningful because patient medical characteristics, treatment approaches, and entry criteria for ART may vary from clinic to clinic.**
For additional birth rate information please visit the CDC website
How does ORH compare with other clinics?
The very best number that you can use to know how a clinic is doing is to look at donor egg pregnancy rates. Use of donor egg takes many variables that impact pregnancy rates out of the equation.
What you are left with is a good reflection of how good a particular clinic is. Look at our donor egg rates. They are world-class and consistent over a multi-year period.
Putting it all into perspective
“There are three kinds of lies: lies, damned lies and statistics.”
-Autobiography of Mark Twain
- All statistical methods assess data from populations.
- But a patient is not a population.
- Each patient has a unique set of circumstances that defines their own specific likelihood of achieving a pregnancy.
- IVF statistics will look good if population data is controlled.
In the words of a famous European infertility expert:
“The patients who are easiest to get pregnant get pregnant most easily.”
Let’s look at two different types of Physicians Practice Statistics, Dr. Lookgood and Dr. Helpall:
|Dr. Lookgood||Dr. Helpall|
|Screen (phone, records)||100||100|
|Patients seen||80 (80%)||96 (96%)|
|Accepted to program||60 (75%)||94 (98%)|
|Cycles promptly started||50 (83%)||94 (100%)|
|Cycles not cancelled||35 (70%)||90 (96%)|
|Transfers||33 (94%)||80 (89%)|
|Transfers, 4 or more embryos||31 (94%)||10 (13%)|
|Pregnancies, ongoing/births||11 (79%)||12 (71%)|
Dr. Helpall treats patients according to a philosophy typical of medicine in most fields, and the philosophy that we believe is the correct one:
Take patients in the order that they come to you, help those who have a chance of being helped, do your best for each individual patient, and let population statistics fall where they may.
As you can see, Dr. Lookgood has a different vision. Take a second look at the same data as reported following the guidelines of the National Registry.
“Pregnancy rate” statistics look like this:
|Dr. Lookgood||Dr. Helpall|
|Pregnancies per transfer||42%||21%|
|Pregnancies per retrieval||40%||19%|
|Pregnancies per cycle||28%||18%|
|Ongoing/births per transfer||33%||15%|
|Ongoing/births per retrieval||31%||13%|
|Ongoing/births per cycle||22%||13%|
The misguided focus on “IVF success rates” has created strong incentives, economic and otherwise, for IVF programs, particularly those that advertise nationally, to “game” the system.
Statistical results summaries, such as the National Registry, actually make the problem worse. Despite the best of intentions the data receives an imprint of authenticity, objectivity, and fairness that they, even theoretically, cannot have.
At Overlake Reproductive Health we are quite proud of our IVF success rates. We strive to treat those patients whom we can help. We don’t try to pre-select our patient population in order to benefit our statistics. Our IVF success rates are “real.”
Here are a few of the methods used by some other infertility treatment centers for achieving “good looking” success rates. And we again remind our readers that the primary theme behind making infertility treatment success rates look good is not to corrupt the mathematical computation but to select the patients and cycles, and hence the data, going into those calculations.
- Move Patients with a good prognosis for success with IUI (Intra Uterine Insemination) to IVF sooner. IUI can be a very successful, cost effective, and less invasive first treatment option for properly selected patients. We routinely achieve success with IUI cycles in patient populations that would have been pushed prematurely to IVF in other centers.
- Classify difficult patients as research subjects: Certain IVF centers enhance their statistics dramatically by the simple expedient of classifying their most difficult patients as “research patients”, and then failing to include them as part of their “real” clinical statistics. This allows such facilities, of course, to maintain their volume of activity, and do the same type of research that is appropriately done at many IVF facilities, while looking better than their peers. Within any group, or age group cluster, of patients there are very wide variations in the likelihood of pregnancy for individuals. The systematic exclusion of the most challenging patients from the clinical statistics enriches the success rate of the reported subset automatically.
- Move challenging patients to donor egg services early: There can be no question that donor egg substitution in circumstances where the woman’s ovaries show some aging effects or where egg quality appears to be somewhat reduced can be very effective in achieving pregnancy. But at what point should individual patients be encouraged to consider this alternative? Any IVF center that directs candidate patients at a relatively early stage toward the donor egg process, especially if this is reinforced by refusing to further provide conventional IVF services to such women, will be assured of achieving “better” IVF success rates.
- Discourage embryo cryopreservation: This is powerful, yet subtle. A patient goes through an IVF cycle, produces, for example, say 6 to 9 embryos, and is advised that her “embryos do not look good enough to freeze.”
Consider what happens when freezing is precluded. First, there will usually be a larger number of embryos transferred than would otherwise have been preferred by the couple, and the “IVF success rate” statistics of the IVF facility will thereby be enhanced. But the statistics will be further improved for an additional, more complex reason. Patients vary in the ease with which embryos will implant in their uterus and produce a pregnancy. A patient may be perfectly normal from this perspective, yet fail to become pregnant with her first fresh embryo transfer. There is a substantial probability that such a “good” patient will then conceive on her subsequent frozen transfer cycle(s). If she does so, she is a statistical failure for “IVF success rate” purposes, since this is calculated from non-cryopreserved cycles, and she will not medically reappear for a second fresh IVF cycle. But if freezing is not done, and if a pregnancy does not result from the first fresh embryo transfer, such patients will likely do second full IVF cycles. And many of them will then become pregnant on this second fresh cycle.
Thus, the discouragement of freezing leads to a group of patients doing repeat fresh IVF cycles which is predictably enriched for better patients compared to what would happen if embryo freezing had been more broadly utilized. The result is, automatically, “better” IVF success rates in the aggregated fresh cycles. And it need not perhaps be added that such an approach enhances the economic benefit to the IVF center by substituting a full IVF cycle for a much less costly frozen transfer cycle.
In conclusion, we would like to express our respect for the integrity of those many physicians in the IVF field who have resisted the extremely strong pressures to modify their programs and policies to optimize apparent “success rates.” Predictably, but unfortunately, these pressures have influenced the actions of some other IVF centers very heavily. Simple formulas, and the reliance on statistics, cannot achieve the desired goals. A system unsound in principle cannot, and should not, be relied upon in practice.
While we are understandably proud of our IVF success rates, with upward trends attributable to an unremitting introduction of cutting edge ideas and technology, it should be noted that a comparison of clinic success rates may not be meaningful because patient medical characteristics and treatment approaches may vary from clinic to clinic.