 Reading Between the Lines:
IVF Statistics
Because
there are numerous ways in which IVF statistics can be stated, IVF clinics can present
their results in a way which shows them in the most favorable light... but does not give
you the whole picture.
Success
Per...
The
Society for Assisted Reproductive Technology (SART) has therefore set the following
guideline: "The preferred way to avoid misleading patients is to report live birth
data per cycle initiated and per egg retrieval procedure." (Practice Committee
Report: Guidelines for Advertising by ART Programs, January 1998)
When
rates are stated per cycle initiated, this means that every patient who enters that
clinic's IVF program is included in the results. Per egg retrieval includes only
those patients who actually underwent oocyte retrieval. (Some women are dropped from the
cycle prior to that point due to lack of adequate response to the ovulation-induction
medication.) SART considers both of these to be realistic; ie: what is your
likelihood of success if you enter their IVF program (by beginning the medications), and
what is your likelihood of success if you actually undergo the egg retrieval procedure_
If an
infertility clinic states its results per embryo transfer (a method not recommended
by SART), they are including in their patient group only those whose embryos successfully
fertilized. Thus, an IVF program can have relatively poor results with their medication
protocols and/or fertilization rates, yet have high success rates per embryo transfer.
per embryo transfer.
Pregnancies
and Live Births
Chemical pregnancies refers to all women who
had a positive pregnancy test following their IVF cycle. Clinical pregnancies
refers to women whose positive pregnancy tests were followed by identification of a fetus
on ultrasound at about seven weeks gestation. Some miscarriages can be expected at
that point, and therefore the live birth rate generally will be lower than the clinical
pregnancy rate. Since you presumably want to know what your chances are of having a
baby (not just becoming pregnant) from IVF, live birth data will give you a better
picture than clinical pregnancy rates.
An ongoing
pregnancy is different from a clinical pregnancy in that it is one which has reached
the second trimester and is therefore quite likely to result in a live birth. It is
considered acceptable to state ongoing pregnancies in place of live births when
quoting statistics from recent IVF cycles, in which some of the patients are still
pregnant and the live birth rate is, thus, not known.
Be
a Careful Consumer
Thus,
before you consider an IVF clinic’s success rates, it is important to note how they
arrive at their rates. Are they quoting clinical pregnancies or live
births, rates per initiated cycle or per oocyte retrieval_
Further,
make sure the IVF program is including all of their data. For example, if they
quote statistics only for "under 40" patients, the numbers will most likely be
higher than if they include all age groups. And be sure that a program is presenting all
their data, not just the selected months or years that they want you to see.
Note,
also, whether the data has been reported to (and thus verified by) SART.
No
Comparison is Truly Accurate
Even
armed with this knowledge, there is no way to truly compare one IVF clinic with
another. Some will exclude potential IVF patients whose medical histories
indicate that they are unlikely to succeed. These IVF clinics will appear to have
better success rates than those who accept everyone who comes to them for
help. Also, some may have more success with couples who have your particular
condition than do others. The SART guidelines (Practice Committee Report:
Guidelines for Advertising by ART Programs, January 1998) specifically caution their
member clinics to make consumers aware that "as entry level criteria are highly
variable for each program, a center-by-center comparison of results is not
valid."
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