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PGS: IVF Success Rates

August 2011 - June 2016

%
Pos HCG
Positive N #
Embryos ET
#
Clinical
%
Clinical
#
sacks
Implantation Rate
OVERALL PGS Frozen Pos HCG 78.3% 231 295 550 176 76.2% 283 51.5%
FET-2 Embryo w/PGS-Pos HCG 83.3% 195 234 489 150 76.9% 256 52.4%
FET-1 Embryo w/PGS- Pos HCG 59.0% 36 61 61 26 72.2% 27 44.3%

Around 60 patients have frozen embryos that have undergone PGS testing, are chromosome normal, and are planning to do FET (frozen embryo transfer) in the next future. ACFS expects similar results in these patients, as above, with a FET with 2 embryo transfer. Also, a number of these patients are older (>37 years old) and have done two stimulation cycles in an attempt to improve their success rates (see #3 below). One important change in the last two years is a decrease in miscarriage rates and a subsequent increase in implantation rates in what ACFS feels is directly related to a proactive approach to miscarriage prevention prior to embryo transfer.

ACFS data for the last four years (August 2011- July 2015) clearly supports our continuing experience that PGS (preimplantation screening) improves pregnancy rates, ongoing pregnancies (clinical pregnancy) and decreases miscarriage rates. ACFS experience during the last four years has also noticed some interesting trends:

1

If a women is able to transfer 2 chromosomally normal day 5 embryos, pregnancy rates are increased by almost 15% (14.57%). Without PGS testing, pregnancy rates are 71.43% with a FET or frozen embryo transfer (ACFS no longer does fresh transfers because of the lower pregnancy rates , up to 30%, in putting embryos back in a physiologically overstimulated cycle that they were gotten from). ACFS believes that FET without PGS data is biased because many embryos that are chromosomally abnormal "stall out" in culture and never reach the blastocyst stage and therefore are not cryopreserved (or frozen). Even if they reach the blastocyst stage and are frozen, there are decreased survival rates when thawed for embryos that are chromosomally abnormal. Thus, the freeze-thaw process acts as a "screen and/or selects" for normal embryos. In other words, if the embryo survives the freeze-thaw process, there is a suggestion that this embryo has an increased chance of being chromosomally normal. ACFS is currently engaged in a clinical study looking at this data and preliminary data suggests it to be accurate.

2

One very important and interesting trend found by ACFS, is the much higher pregnancy rates with transferring 2 embryos as opposed to transferring 1 embryo. This is especially true for women 37 or older. Most one embryo transfers are either in younger patients who want a "zero" risk of twins or older patients (37 or older) who only have 1 chromosome normal embryo to transfer. Some young patients do not do chromosome testing, whereas almost all of the older patients do. In the above data, most of the 1 embryo transfers without PGS are in young patients (66.67% pregnancy rate); whereas 1 embryo transfer with PGS is in older patients (42.86%).

It is ACFS belief, that although chromosome testing goes a long way to "eliminating" age as a factor, the data shows that if a younger patient transfers 2 chromosome normal embryos and the older patient (37 or over) transfers 2 chromosome normal embryos; both will have the 83.3% success rates, but the younger patient is at increased risk of twins (28%) whereas the older patient (37 or over) will get a singleton (one baby). This suggests that although chromosome testing (PGS) goes a long way to "wipe out" age as a factor, there are still "age-related" factors in the embryo of an older patient. This data strongly suggests that the goal is to transfer 2 day 5 (blastocyst) chromosome normal embryos especially in older patients. In light of this information, ACFS recommends that patients 37 or older consider two stimulation cycles with freezing the eggs on the first attempt. By doing two stimulation cycles, ACFS will have twice as many eggs/embryos; therefore having twice as many embryos that undergo PGS screening.

An important point in this decision is to know that ACFS success rates with frozen eggs is the same as with fresh eggs. Also, by doing two stimulation cycles, with freezing the first set of eggs, as opposed to doing two complete IVF attempts, ACFS saves you around $6000-7000- by only having to do one fertilization procedure (ICSI), one advanced culture to blastocyst stage (day 5) and only one PGS (preimplantation) testing. The down side of two stimulation cycles is that you may not need to do them and one stimulation cycle will be enough to have a successful outcome. In women 37 and older that have a high resting follicle count (BAF- basal antral follicle count), low FSH and high AMH, may be fine with only one stimulation attempt because they are predicted to make a high number of eggs/embryos (if stimulated appropriately, which they will be).

3

Although clinical pregnancies (evidence of a gestational sac at 6+ week ultrasound) are similar with FET with or without PGS, ACFS data shows a 9-10% decrease in miscarriage rates with PGS testing; as well as eliminating the risk of a Down's pregnancy and/or other chromosome abnormalities. Also FET (frozen embryo transfer), without PGS testing, is again bias. Most embryos that are chromosomally abnormal do not even implant and/or if they do, result in an increased risk of miscarriage (70-80% of miscarriages are do to the embryo being chromosomally abnormal). This is evidenced by the fact that implantation rates with FET with PGS are 41.28% and FET without PGS are 29.58%

Patients are cautioned regarding making comparisons of success rates between IVF clinics based on the clinic - specific data reports released by the Society for Assisted Reproductive Technology ( SART ) and the Centers for Disease Control ( CDC ). Although SART issues a statement that specific clinic data should not be used for comparison, the fact is that they are used by patients and clinics alike for that purpose. There are many factors that influence IVF success rates and many variables exist among individual clinics that make comparisons almost impossible based on the released data. Some of these problems of the clinic - specific data reports include:

  • The SART data are not divided into repeat and new IVF patients. For example, patients, 34 and younger, in a particular clinic may have repeated failed IVF attempts before and would have a poor prognosis even though they have a favorable age. ACFS DOES NOT DO THIS.
  • The population mix of individual clinics is totally unaccounted for in the SART-released data. For example, a clinic that pushes IVF treatment ( which may be justifiable in many circumstances ) as the primary modality of therapy for patients with non - tubal infertility may have higher success rates than a clinic that offers IVF to its patients only after they have been unsuccessful with "low" tech treatments like IUI (intrauterine insemination). The different population of patients being treated may largely account for the higher success rates. ACFS DOES NOT DO THIS.
  • The criteria for patient acceptance and for cancellation prior to egg retrieval vary among clinics and, as such, influence pregnancy rates tremendously. For example, a clinic that does not accept patients beyond a certain age ( for example, age 40 ) and patients with poor ovarian response (high basal FSH levels, low AMH levels and abnormal clomiphene citrate challenge test ) will have higher success rates than a clinic that does not exclude these patients. Again, the higher success rates will be largely attributed to the patient population. ACFS DEFINITELY DOES NOT DO THIS.
  • The policy for fresh embryo transfer and embryo cryopreservation is very different among clinics and greatly influences the pregnancy rates. For example, clinics that culture all the embryos and transfer only the morphologically best embryos may have better fresh pregnancy rates than clinics that culture only the desired number of embryos for transfer and freeze all the rest at the pronuclear stage. There are many advantages in freezing excess embryos that include giving patients another chance for embryo transfer without repeating stimulation and egg retrieval and reducing the incidence of a multiple pregnancy. ACFS ONLY DOES FROZEN EMBRYO TRANSFERS WE HAVE FOUND UP TO A 30% HIGHER PREGNANCY RATES THAN TRANSFERRING ON A FRESH CYCLE THAT IS PHYSIOLOGICALLY OVERSTIMULATED. ACFS STRONGLY BELIEVES THAT PGS (preimplantation screening) SIGNIFICANTLY IMPROVES PREGNANCY RATES, ONGOING CLINICAL PREGNANCIES AND DECREASES MISCARRIAGE RATES. PGS TESTING REQUIRES THAT ALL EMBRYOS BE FROZEN WHILE YOU AWAIT THE RESULTS. THIS WORKS OUT PERFECTLY SINCE ACFS DOES NOT RECOMMEND FRESH TRANSFERS.

These are only some of the examples that can be listed that clearly invalidate comparisons between IVF clinics based on the released SART clinic - specific data reports.

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