New Technique
Raises Pregnancy Odds Without Multiple Births
April 9, 2004
Reuters Health
NEW YORK
(Reuters Health) -
Combining sperm
and egg in the lab and then transferring the
resulting embryo into the mother is a common
treatment for infertility. Now, new research
indicates that implanting a slightly older
embryo can increase the chances of pregnancy,
which in turn can lower the risk of multiple
births.
Transferring
newly formed embryos produces notoriously low
pregnancy rates. To address this problem, a
doctor will often transfer more than one embryo
into the womb. Although this practice increases
the chances of pregnancy, it also raises the
risk of carrying twins.
With recently
developed laboratory techniques, it is now
possible to grow embryos to a more advanced
stage, when they reach the stage known as "blastocysts."
Several reports have shown that embryos are more
likely to implant and grow in the womb if
they're transferred at the blastocyst stage
rather than at the newly formed stage.
The higher implantation rates achieved with
blastocyst-stage embryos have allowed doctors to
decrease the total number of embryos
transferred. When just one blastocyst is
transferred, the risk of twins is eliminated.
In the current study, Dr. David K. Gardner
and colleagues, from the Colorado Center for
Reproductive Medicine in Englewood, assessed the
pregnancy outcomes of 48 women who had one or
two blastocysts transferred. The findings are
reported in the medical journal Fertility and
Sterility.
The implantation and pregnancy rates in the
single-blastocyst group were both 61 percent,
the researchers note. Although a slightly higher
pregnancy rate of 76 percent was seen in the
double-blastocyst group, nearly half of the
pregnancies involved twins, a problem not seen
in the single blastocyst group.
Although the findings suggest that high
pregnancy rates are attainable with single
blastocyst transfer, further studies are needed
to determine if there are certain patient groups
that benefit most from this technique, they add.
SOURCE: Fertility and Sterility, March 2004.
