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Understanding The CDC Report on IVF Success Rates
a blog by Kim Griffiths, January 19, 2013
We’ve all been there. Scouring the internet for information on the best fertility clinics in the country based on IVF success rates. Guilty as charged. But, did you know that there is a lot more to the CDC and SART reports than meets the eye? It turns out that while the CDC requires fertility clinics to report their data based on the same guidelines, that data can mean different things at the clinical level.
Here is what I like to call the Infertile’s Guide to Understanding the IVF Success Rate Report:
- The CDC takes three years to collect the data for each year’s cycles. This is because the outcome of pregnancies is not immediately known. Additionally, analyzing data and preparing it in a uniform reporting style takes time. I’m envisioning an abacus, but I’m sure that is not how they keep track of these things. While the CDC report contains the most current national data, your fertility clinic will be able to provide the most up to date statistics for that facility.
- Data is not the same across the board. Although the CDC guidelines instruct clinics on how to report their cycles, there are individual variables that impact success rates. Imagine that! Research having variables? I just had a flashback to grad school. Apparently, clinics that complete greater numbers of IVF cycles will show less variation year to year than clinics that complete fewer cycles.
- Some clinics accept “more difficult” cases into their program where other programs have age and diagnosis cut offs. Our fertility declines with age and patients with ovarian reserve issues can be poor responders during an IVF cycle. Some clinics will not accept these patients into their program without using donor eggs. That patient's potentially failed cycles will lower the clinic's success rates.
- Success rates are reported per cycle, instead of per patient. Patients who cycled several times and failed before finally conceiving may lower a clinic’s success rates because each of her cycles counts as individual failures and only one success.
- Cancellation rates vary. Some clinics cancel more cycles than others. That leads to a lower percentage of live births, but may increase the number of retrievals resulting in live births and the number of transfers resulting in live births. Did I lose you on that one? In short, depending on how strict a clinic is with their cancellation guidelines, their success rates can change.
- Natural cycles (without medication) and medicated cycles are included in the same data. Natural cycles typically produce fewer eggs for retrieval, thus fewer embryos to become live births.
- Number of embryos transferred varies from clinic to clinic. Some clinics opt for double embryo transfers (or more in those over the age of 35), while other clinics encourage Single Embryo Transfer (SET). Transferring more embryos does not increase your odds of getting pregnant, but it does increase the risks associated with a multiples pregnancy, can result in pregnancy loss, or lead to premature birth.
Of course then you factor in things like egg quality, sperm quality, the skill of the doctors, the use of advanced equipment, the health of the patient, and potential problems on a chromosomal level. All of these things can impact a fertility clinic's success rates. So, when it comes to looking at fertility clinic IVF success rates, make sure you understand what you’re really looking at.
To talk about IVF and other matters of the uterus, you can find Kim on FertileThoughts.com as KimAtFertilityAuthority.