Lowering the
Chances of Multiple Births Charlotte Meyers
Many doctors have responded to the latest
consequence of the success of an in vitro fertilization. Often I.V.F is often too successful and since
1980 when that technique became available in the
In I.V.F a woman
is given ovulation inducing hormones to produce multiple eggs. The eggs are retrieved, fertilized, and transfered back into her uterus. The more embryos that are transferred, the
more likely it will be that the woman will have multiple children. In order to try to get one single baby,
doctors are focusing on transferring fewer embryos and on developing a more
sophisticated way to find the healthiest embryos. Although efforts have lowered then rate of
triplets born substantially, doctors have not made a dent in the twin
rate. That is because many doctors and
patients have hesitations about ensuring a single birth. To ensure a single birth only one embryo can
be transferred.
The main obstacle in single embryo
transfer is the lower success rate. With
all that pressure on the one embryo, clinics are trying very hard to find the
embryo that is most likely to succeed.
Usually selecting embryos was based on a physical examination of their
morphology. However, morphology does
reveal everything and many embryos that look great under microscopes have
undetected chromosomal abnormalities.
One method of taking out the unhealthy embryos is to leave the embryos
in a Petri dish for five days, two more than usual, in order to allow more time
for hidden chromosomal abnormalities to show up. Other doctors are turning to genetics to
obtain embryos without missing chromosomes.
This screening selects healthy embryos in families with histories of
genetic diseases. However, there is some
concern that this process an damage embryos. All these tests are not really getting anyone
anywhere because women are still refusing to have just one embryo put in. Many women do not think having twins is risky
and in fact many are happy to speed the process of completing their
family. Carrying twins or higher- order
multiples raise the risk of premature births, low-birth-weight babies, the
possibility of death in very premature infants, long term health problems and
pregnancy complications. Even with all
those risks women take comfort in the improvements in care. The survival rate
for newborns over two pounds three ounces is 85 percent. Many people also blind themselves by only
seeing the adorable twins in the double strollers and not the twins that do not
make it out of neonatal intensive care.
Many doctors think that the biggest
problem is coming from ovulation induction.
If ovaries are too aggressively stimulated with hormones a woman can
produce a nest full of eggs and increase the risk of having triplets,
quadruplets, and even sextuplets. All
ovulation induction cycles should be closely monitored and in some cases
cancelled if there are too many embryos.
With this new information there are many
new possibilities. With some more
research women could potentially chose the number of children she wants to
have. Also, these treatments could one
day be used as a way of achieving population control.
References:
1. http://www.aium.org/images/patImgGallery/5.jpg
2. http://www.nytimes.com/2008/02/19/health/19mult.html?_r=1&ref=science&oref=slogin