January 13, 2012
Using 3 Or More Embryos Does Not Raise IVF Odds
A new British study of fertility treatments found that women who receive three or more embryos during in-vitro fertilization treatments have no greater chance of having a baby than those who get just two embryos.
The researchers concluded that transferring three or more embryos "should no longer be supported in women of any age".
Women undergoing IVF treatment are frequently implanted with three or more embryos to maximize the odds of at least one developing into a healthy baby. However, the issue of how many embryos a women should receive during treatment has been controversial for years, because multiple births are linked to higher rates of medical problems for both mothers and infants as well as greater healthcare costs.
"Women who have gone through infertility treatment want the best chance of having a baby, but we need to explain that the data shows transferring more embryos doesn't actually do that," study co-author Dr. Scott Nelson, chief of reproductive and maternal medicine at the University of Glasgow, told the Associated Press (AP).
Many authorities in western Europe recommend a single embryo transfer for women under the age of 37, and a maximum of two embryos for women 37 to 40. Three embryos is frequently the legal for women over 40.
However, guidelines are fairly lax in the U.S. by comparison, and regulation is typically lacking. The subject of multiple births was brought into the public spotlight in 2009, when so-called “octomom” Nadya Suleman gave birth to octuplets after her doctor transferred 12 embryos during IVF treatment. Ms. Suleman had already had six children through IVF.
Most fertility treatment in the U.S. is privately funded, costing at least $10,000 per cycle, something experts say encourages the use of more embryos in hopes it will improve the odds of pregnancy.
The American Society for Reproductive Medicine recommends single embryo transfers for women under 35, although those guidelines are not enforced. For women aged 35 to 37, they recommend two to three embryos, and for women aged 38 to 40 they advise three or four embryos.
In the current study, Nelson and colleagues analyzed data for all of the 124,000 IVF cycles in Britain between 2003 and 2007, along with the 33,500 resulting births.
The women were 18 to 50 years old and had varying histories of infertility. The IVF treatments consisted of eggs fertilized with sperm in a lab dish and then placed in the womb.
For women under 40 who had two embryos transferred, the overall live birth rate was 33 percent, dropping to 25 percent among women under 40 with three embryos transferred.
Nelson said that might be due to the higher risk of miscarriage in a multiple pregnancy, and that miscarrying a single fetus would jeopardize the entire pregnancy.
For women over 40, the live birth rate was 13 percent regardless of whether two or three embryos had been transferred.
Nelson said women undergoing IVF treatments may pressure their doctors to transfer more embryos, believing it may increase their odds of having a baby and avoiding further treatments.
"Doctors may feel if they don't do what their patients want, they'll just go down the street to another clinic," Nelson told the AP.
"They need legislation to help control the situation."
In Britain, which has tougher policies than those in the U.S., transferring three embryos in women under 40 is prohibited, and doctors who do so for a woman of any age must explain their actions to the fertility regulator.
In 2010, 65 percent of embryo transfers in Britain involved two embryos, while 31 percent used single embryo transfers. The rest involved the transfer of three embryos.
By comparison, in the U.S., data from 2009 showed about 52 percent of embryo transfers involved two embryos, while 23 percent used three embryos. Nearly 12 percent involved four to seven or more embryos, with just percent using a single embryo, the USAToday reported.
Multiple births carry a higher risk of miscarriage and pregnancy complications such as high blood pressure and diabetes. Additionally, twins and triplets are more likely to be born premature, and to have an elevated risk of developmental problems.
The study was published in Thursday's issue of Lancet.
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