One Embryo Better Than Two in In Vitro Fertilization

Single embryo transfer more effective and safer than double, says study.

ByKIM CAROLLO, ABC News Medical Unit
December 21, 2010, 1:44 PM

Dec. 21, 2010— -- Shortly after Nadya Suleman gave birth to octuplets in January 2009, the children's births went from being miraculous to being scandalous. Word spread that her doctor implanted the so-called "Octomom" with six embryos through in vitro fertilization (IVF).

One of the main reasons the Octomom case generated so much controversy is that fertility experts say the trend in the field of reproductive medicinehas been steadily moving away from multiple embryo transfers.

"The single embryo transfer is the way of the future," said Dr. Jeffrey Fisch, medical director of the Sher Institute for Reproductive Medicine in Las Vegas, Nev.

A new study published in the British Medical Journal validates that growing trend. The study found that only 27 percent of women who received single embryos gave birth to babies, compared to 42 percent of women who received two embryos -- but multiple embryo implants also accounted for about far more multiple births, which are associated with medical complications including a higher risk of pre-term delivery and gestational diabetes.

If a single embryo transfer is unsuccessful and is followed by a frozen embryo transfer, however, the birth rate is about equal to the birth rate of double embryo transfers, however.

Doctors say the study offers proof that single embryo transfers are an effective and safer way for women to have children through in vitro fertilization, though it's difficult to convince patients.

"It's a useful study," said Fisch. "Anything that moves the public in general to accept the idea that one embryo can make a baby is a move forward."

The researchers, led by David McLernon, a research fellow in medical statistics at the University of Aberdeen in Scotland, analyzed eight different studies that compared the outcomes of single embryo transfers to double embryo transfers. More than 1,300 women were included in the analysis.

All the women in the study received embryos that were two or three days old. Fertility experts say that used to be the most common type of transfer, but now, more and more women are getting embryos that are five days old.

"There's natural selection that occurs, so the embryos that survive to day five are the most viable and likely to survive through pregnancy," said Dr. Jamie Grifo, director of the fertility center at New York University Langone Medical Center.

Grifo said that more recent studies, including one he co-authored, show that five-day-old embryos are associated with a 63 percent pregnancy rate, a rate he says is higher than for two- or three-day-old embryos.

"The [current study's] biggest limitation is that they're looking at earlier stage embryos and there's a move in the field to move toward five-day embryo transfer," said Fisch.

In an accompanying editorial, Allan Templeton, professor of obstetrics and gynecology at the University of Aberdeen, said many fertility specialists are more concerned with birth rates than patient safety. As a result, he said, they don't stress the importance of single embryo transfers. He said single embryo transfer rates are the lowest in the U.S.

Dr. Richard Grazi, director of Genesis Fertility & Reproductive Medicine in Brooklyn, N.Y., said there's a lot of pressure on doctors and patients to see success after the first cycle of IVF.

"IVF is the most regulated medical specialty in the U.S.," said Grazi. "Every IVF center in the U.S. has to report every IVF and its outcome to the Centers for Disease Control and Prevention."

That means that if a patient gets pregnant on the second cycle, it's only a 50 percent success rate. Those percentages, said Grazi, mean a lot to doctors and patients, who can look at the numbers on the Internet. If double embryo transplants are going to result in more pregnancies, then doctors and patients may be more inclined to choose them.

But doctors say they do their best to emphasize the benefits of single embryo transfer, though it's difficult to convince patients of the benefits. Cost is one of the biggest factors. In vitro fertilization procedures can cost thousands of dollars, and medical insurance does not often cover them.

"It is cheaper for patients to do one transfer procedure than to do two transfer procedures," said Dr. Rick Paulson, professor of obstetrics and gynecology at the University of Southern California's Keck School of Medicine in Los Angeles. "Until we have universal medical insurance that pays for infertility treatment, this factor is always going to be important."

"Patients think 'two for the price of one,'" said Dr. Steven Lindheim, professor of obstetrics and gynecology at the University of Cincinnati College of Medicine's Center for Reproductive Health.

Even though the study showed a fresh single embryo transfer followed by a frozen embryo transfer can lead to a live birth, it's still a second procedure and as a result, an additional cost.

And although multiple births can be medically dangerous for mothers and children, many women actually want twins.

"Many patients, especially older ones, consider twins a good outcome," said Paulson. "They know that if they are having fertility treatment at the age of 40, having twins means not having to worry about coming back for fertility treatment when they are 42, and when success rates will be even lower."

Older women are also not the best candidates for single embryo transfers, Grazi said. Their embryos are less likely to be viable, and older women are also far less likely to have multiple births, so the complications linked to multiple births aren't relevant to them.

While it's illegal in some European countries to transfer more than one embryo, doctors say that type of regulation would never catch on in the U.S. In addition to the financial pressures of infertility, it's also psychologically devastating.

"When you've been struggling with this devastating situation for years and sometimes even decades, it's probably best not to second-guess the decisions these couples make," said Grazi.

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