U.K. Tries to Rein In Fertility Treatments by Limiting Embryo Implants to Two
But because the guidelines are "loose," each case can be evaluated
individually, he says. "Sometimes we look at the embryos, and they are not
growing as fast, don't look as likely to implant, so we might put back
more," he says.
Sergio Oehninger, MD, professor of obstetrics and gynecology at the Eastern
Virginia Medical School and director of the division of reproductive technology
at the Jones Institute for Reproductive Medicine in Norfolk, agrees with
Goldfarb about the need to consider each case separately.
He tells WebMD that the two embryo limit is "common in Europe. I think
that is already the case in German and Sweden, and now the U.K. is taking the
same approach." That approach may help explain why in vitro fertilization
success rates in the U.S. tend to be better than the rates in Europe. "If
you implant fewer embryos, the chances are that you will have fewer
pregnancies," he says.
Oehninger says the limit on embryos is one element in an overall "softer
approach to stimulation than we have in the U.S. -- where we take an aggressive
approach to stimulating the ovary to produce more eggs that can then be
fertilized to produce more embryos."
At the Jones Institute, which was the site of the first successful in vitro
fertilization procedure in the U.S., Oehninger says there is now a shift toward
"extending the culture of embryos from day 2 or 3 to day 5 so that we are
actually transferring a blastocyst, or more mature embryo. This allows us to
transfer only two and get a good success rate with very little risk of
multiples." However, the blastocyst transfer is "not yet universally
available," he says.
Even without blastocyst transfer, Goldfarb says the rate of triplet births
associated with in vitro fertilization has decreased dramatically in the last
"Today when we have a young patient, we implant two embryos and our
success rate is better than 50%; 10 years ago we had to implant four embryos to
get a 20% to 25% success rate. That more than doubled the chance of triplets.
Now the [triplet] rate isn't zero, but it's less than 5%," says
- Health officials in England are limiting the number of embryos that can be
implanted in a woman for in vitro fertilization, in an effort to stem the
number of multiple births.
- Experts argue that the new policy is too rigid, and the number of embryos
to be implanted should be decided on an individual basis.
- In the U.S., doctors can reduce the chance of having triplets by using
improved techniques, varying the number of embryos by the age of the woman, and
allowing the embryo to grow a few extra days before implantation.