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The interpretation of in-vitro fertilization
(IVF) pregnancy rates can be very confusing for patients.
SRM’s position is that pregnancy rates alone should
be presented with additional information on what is considered
a pregnancy and/or how many embryos are transferred at a time.
Why? Pregnancy rates can appear higher
because a higher number of embryos are transferred. To make
sure the patient is comparing “apple to apples”,
average number of embryos should be presented. For example,
a pregnancy rate that is 30% where an average of 2 embryos
are transferred is not necessarily worse than a pregnancy
rate that is 50% where an average of 4 embryos are transferred. In
general, the number of embryos transferred increases as a
woman gets older to compensate for the increasing chance that
an older woman will have a miscarriage.
Multiple gestations refer to a pregnancy in which two or
more fetuses are present in the uterus. At SRM, we consider
multiple gestations as a complication, even twins. However,
given the nature of IVF and the desire to acheive a pregnancy,
physicians will counsel and advise you on the number of embryos
to return to your uterus based on your individual medical
situation. To learn more about multiple gestations, click
here.
SRM presents a clinical pregnancy rate which is defined to
be a pregnancy that has been confirmed to have a good fetal
heart rate at 7 weeks of gestation (or approximately 5 weeks
after an embryo transfer). This pregnancy rate will always
be lower than a pregnancy rate defined by a positive home
or serum pregnancy rate because of the inevitable pregnancy
loss rate that occurs in some women. In other words, not every positive pregnancy
test at 4 weeks of gestation develops into a viable pregnancy
with a good heartbeat 3 weeks later.
More information on pregnancy rates can be obtained from
the Center
for Disease Control and the American
Society for Reproductive Medicine.
Revised May 15, 2007
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