Success Rates

Assisted Reproductive Technology (ART)

In reading program brochures or browsing the internet, patients with infertility are often exposed to a bewildering assortment of graphs, tables and numbers, especially regarding “success rates” and individual assisted reproductive technology (ART) statistics.

The term ART is meant to encompass all the various techniques of in vitro fertilization (IVF) including those using embryos derived from a woman’s fresh eggs or a donor’s eggs and either fresh or frozen embryos. (The list of included techniques continues to grow as the repertoire of IVF continues to expand.) The educated patient must be able to decipher meaningful data from these numbers; including their specific chances of achieving the ultimate goal — a baby.

Program statistics are mainly useful in the context of a discussion with a reproductive endocrinologist, as any specific patient’s chances of conception may be decreased or increased by individual factors, especially their medical history. It is also important to remember that what typically draws attention are the individual program statistics from in vitro fertilization. These statistics say nothing about the probability of conceiving as a result of the many other medical and surgical techniques that are used to treat infertility.

Understanding the SART Clinic Report

Both the American Society for Reproductive Medicine (ASRM) and the Centers for Disease Control (CDC), which compile the results of nearly every ART program in the United States, caution prospective patients not to compare statistics across programs. Despite this warning, it is natural for patients to do just that. Here is an example to illustrate the problem in doing so:

Suppose 10 patients enroll for treatment at Clinic A and all undergo IVF, with 7 being successful. Clinic A can boast a 70% success rate. Now suppose that those same 10 patients had enrolled instead in Clinic B, and that Clinic B takes a more conservative approach to using IVF. In Clinic B, only 5 patients undergo IVF, with more traditional treatment given to the remaining 5 patients. Now supposed that all 5 patients treated with the non-IVF approach conceive, but only 2 of the 5 who undergo IVF conceive. Although 7 of 10 patients are pregnant at Clinic B, the “success rate of Clinic B is only reportable as 40%. Because the focus is only on IVF outcomes, Clinic A has a “success rate” that is 30% higher than Clinic B.

Yet, the actual number of patients who are successful is identical in both programs!

A different type of problem arises in comparing statistics from two IVF programs. It is well-known that blastocyst transfers are associated with the highest live birth rates per transfer (LBR). Transfers of blastocysts that have been screened through preimplantation genetic testing (PGT) yield the highest LBR of all. Thus, clinics that restrict transfers to those patients whose embryos have reached the blastocyst stage will always very high LBR. That LBR will further increase as the utilization of PGT increases. Clinics that do not have such restrictions and do not have high utilization of PGT, meaning that they offer transfer of cleavage stage embryos, will always have lower LBRs, because the average cleavage stage transfer LBR is half of the LBR with blastocyst transfers, and PGT cannot be done with cleavage stage embryos.

Comparing LBRs of clinics with different policies does not indicate anything about the total number of patients undergoing IVF who walk away with a baby.

At GENESIS, we believe that patients whose embryos are not expected to survive the transition to the blastocyst stage still deserve a chance to conceive with cleavage stage transfer, and the literature doe support that many babies can be born this way. This is particularly important for women of advanced reproductive age and those diagnosed with diminished ovarian reserve.

These are two of many potential problems in using IVF statistics as the sole measure of a program’s quality. All consumers and patients should be aware that many other factors go into the quality assessment of fertility practices. If you are a patient undergoing active assessment or treatment, you should feel comfortable in discussing the quality measures that are important to you.

Success Factors in ART

Age / ovarian reserve

There is little doubt that the woman’s age at the time of treatment is one of the most significant and predictable factors for success with ART. As age increases, a significant decline in pregnancy rates is seen. More than likely, this is a direct consequence of a decline in oocyte (egg) quality as the ovaries age. It should be noted that younger women may also be found to have diminished egg quality – so called diminished ovarian reserve – and that this will impact her chance of success with ART as well as her expected time frame to achieve a pregnancy independent of the reason for which ART has been recommended.

Embryo quality

Embryo quality is yet another factor which may influence pregnancy rate. As a general rule, the better the quality of the embryos replaced, the higher the chance that at least one will implant in the uterus. Embryo quality at GENESIS is assessed at different stages of IVF using the visual inspection of the embryos at either the cleavage stage or the blastocyst stage.  Most commonly, the criteria used to assess embryo quality are based on the cell morphology, or appearance, which in the cleavage stage (usually 3 days from egg retrieval) will include cell (blastomere) number, size, shape and degree of fragmentation. At the blastocyst stage (usually 5 days from egg retrieval) the level of expansion of the embryo as well as the appearance of different components, the inner cell mass (the precursor of the fetus) and the trophectoderm (precursor of the placenta and membranes.)  A different and sometimes more accurate way of assessing embryo quality is by genetic testing (preimplantation genetic screening).

The most difficult cases are often evaluated using time-lapse imaging. Most recently, the use of artificial intelligence combined with time-lapse imaging has been proposed as a technique to identify the best embryos for transfer. Many clinics, including GENESIS, are beginning to explore this new avenue of embryo assessment.

Our most recent SART statistics demonstrate our success in achieving excellent clinical pregnancy rates per embryo transfer procedure.

The prevention of high order pregnancies (triplets or more) is a complication of ART that we take very seriously at GENESIS. Even twin pregnancies are associated with poorer outcomes than singletons, so our usual focus is on single embryo transfer. We make every effort to follow the guidelines issued by the ASRM to limit the number of embryos transferred. Whenever clinically indicated, we recommend transfer of a single embryo so that multifetal pregnancy can be avoided. As responsible practitioners, we will sacrifice a few percentage points in statistics if that means fewer twins and triplets, because the healthiest pregnancies usually come with one baby at a time.