Suzanne Leigh, Medical Tribune News Service
A new laboratory procedure offers fresh hope to women who have
failed to become pregnant after repeated attempts at in vitro
fertilization (IVF).
In a study in the August issue of the journal Fertility and
Sterility, doctors found that women who had been unsuccessful with
traditional IVF had a 40 percent chance of becoming pregnant after
a single treatment using blastocyst transfer.
Unlike regular IVF procedures that involve transferring embryos
to the uterus on the second or third day after fertilization, the
new technique entails culturing the embryos for an additional two
to three days in a medium that contains life-sustaining nutrients.
This longer development period enables clinicians to determine
which of the surviving embryos -- or blastocysts as they are called
at this stage -- are the most suitable for implantation.
In the study, researchers led by Dr. Jose. R. Cruz of the
division of reproductive endocrinology at the George Washington
University Medical Center in Washington, D.C., compared the results
of 15 women who chose to undergo blastocyst transfer with 22 women
who opted for traditional IVF. The average ages of the two groups
were 35 and 36 respectively. All participants had experienced three
or more failed IVF cycles.
When Cruz's team compared the success rates of the two groups,
they found that two participants in the regular IVF group, or 9
percent, had become pregnant, versus six participants, or 40
percent, in the blastocyst group.
One of the leading advantages of blastocyst transfer is that
because only robust, high-quality embryos are used it precludes the
need to implant more than two embryos, which typically happens in
traditional IVF and can lead to multifetal pregnancies (three or
more babies).
In a second article in Fertility and Sterility, researchers from
the division of reproductive endocrinology and infertility at
Stanford University in Stawnford, Calif., compared the percentage
of women who got pregnant with blastocyst transfer using one, two
and three embryos. Among 55 participants, 29 elected to have two
embryos transferred, 24 had three transferred and two had one
transferred.
Dr. Amin Milki and colleagues found that both women who opted
for single embryo transfer failed to get pregnant. Among the 29
women using two embryos, 18 had viable pregnancies confirmed at
nine weeks and seven of those pregnancies were twins. Among the 24
women using three embryos, 14 had viable pregnancies confirmed at
nine weeks; seven of those pregnancies were twins and four were
triplets.
``Although it may be difficult for patients to accept the
concept of transferring fewer embryos, we strongly recommend that
patients be encouraged to have only two blastocysts transferred,''
said the authors.
Using two embryos gave the patient ``all the benefits of this
new technology while eliminating the risk of high-order multiple
gestations,'' they said.
One surprising effect of blastocyst transfer, noted in a third
report in Fertility and Sterility, was that it leads to a
preponderance of male babies. In a study led by Yves Menezo of
Institut Rhonalpin in Bron, France, researchers found that
blastocyst transfer at three infertility clinics resulted in the
births of 138 girls and 193 boys.
This higher incidence of boys may be explained by the fact that
male embryos tend to develop faster than females at the blastocyst
stage thus making them better candidates for implantation, said the
authors.
