Researchers have suggested that implanting multiple embryos for In Vitro Fertilization (IVF) may do more harm than good. This finding appeared in the current online version of the journal Lancet. The study argues against common practice of implanting multiple embryos in order to maximize a woman’s chances of conception during in vitro fertilization.
Researcher Liv Bente Romundstad, of the fertility clinic at St. Olav’s University at Trondheim, Norway, said, “The number of embryos to transfer in an IVF cycle should basically be restricted to one. The reason for this is the higher rates for complications.”
Dr. Eve Feinberg, a reproductive endocrinologist at the Illinois Fertility Centers, however disagrees and said that she implants up to four embryos for women age 40 and over. Feinberg, who considers herself a firm believer in each woman maximizing her own chances of conception, only uses one or two embryos for patients under 35.
The study, on the other hand, stated that even women over 40 should only have two embryos. “In both [age] groups, transfer of three embryos did not increase the live birth rate over that seen after the transfer of two embryos, but was associated with an increased risk of adverse prenatal outcomes," researchers said.
Researchers Scott Nelson and Debbie Lawlor, of the University of Bristol, analyzed 124,148 IVF cycles in clinics in the United Kingdom between 2003 and 2007, resulting in more than 33,500 live births. The women were 18 to 50 and had varying histories of infertility. During IVF, eggs are fertilized with sperm in a lab dish and then put in the womb. They divided the women into two age groups: one below 40 and one above 40. In the younger age group, the rates of live births with implanting three embryos were lower than the rates associated with two embryo implantations. In the older age group, both two and three embryos yielded the same success rates.
For women under 40 who had two embryos transferred, the live birth rate was 33 percent overall. With three embryos, that dropped to 25 percent, though researchers weren't sure why. Nelson said it might be due to the higher risk of miscarriage in a multiple pregnancy and that miscarrying one fetus would jeopardize the entire pregnancy. For women over 40, the live birth rate was 13 percent whether they had two or three embryos transferred.
What most experts agree is that age is also a key factor in determining the effectiveness of IVF treatment. The Lancet study found that “the live birth rate was noticeably lower in older women than in younger women, irrespective of the number of embryos transferred.” “Age is everything when it comes to the procedure – well, actually, age is everything when it comes to reproduction,” Feinberg said. “With age comes a downfall for pregnancy – with or without IVF.”
Feinberg recommends that all women go by the statistics. “It’s so important to find a doctor and clinic that has success,” she said. She suggests checking Centers for Disease Control and Prevention’s website at cdc.gov for statistics on each doctor and clinic’s success rates.
“Everybody is different and everybody is different,” said Gina Kremer, a spokeswoman for Illinois Fertility Centers. “But there are definitely ways to maximize your chances.”
Dr. James Grifo, director of the New York University Fertility Center, agreed doctors should avoid using more than three embryos. But he said it was warranted for some, such as older women with a history of failed treatment. “I spend a lot of time trying to talk patients out of the three-embryo transfer and you can't always do it…My last set of triplets was a patient who demanded I put back three embryos,” she said. Grifo said she wasn't swayed by the data. “She delivered the triplets and they're fine, but I wasn't happy about it.”
“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,” said Dr. Scott Nelson, head of reproductive and maternal medicine at the University of Glasgow, who co-authored the study.
The American Society for Reproductive Medicine recommends single embryo transfers for women under 35, but there is no enforcement of that. For women 35 to 37, they advise two to three embryos, and three to four embryos for women ages 38 to 40. The U.K. has tougher policies. Transferring three embryos in women under 40 is banned. And if doctors transfer more than three embryos, they must explain their actions to the fertility regulator. In 2010, about 65 percent of embryo transfers involved two embryos and 4 percent used three. The rest were single embryos.
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