State of the ART Fertility Treatments
Although PGS hasn’t panned out as a way to significantly raise overall IVF success rates, fertility experts are excited about other promising technologies. One is called metabolomics: Instead of analyzing the embryo itself, scientists evaluate the fluid in which the embryo is cultured – essentially its bath water. “Good embryos use the components in the fluid differently from embryos that are bad,” says Yale’s Dr. Denny Sakkas, who also serves as chief scientific officer at Molecular Biometrics, a company that’s developing an embryo evaluation test based on metabolomics.
Dr. Sakkas’ company has tested the technique in 1,500 single-embryo transfers and expects it to be available in Europe next year and in the United States in 2010. “We’ve been able to show consistently that the higher the score, [from the test] the greater the chance of establishing a pregnancy,” he says, adding that he predicts this technology will improve pregnancy rates by 10 to 20 percent and make it more likely women will conceive in their first round of IVF. He also expects the test to increase the success rate for single-embryo transfers, thereby reducing the number of twins and triplets. “You can do it an hour before the embryo transfer, and it gives you something valuable to help make the decision,” about which embryo(s) to transfer, he says.
In other labs, researchers are investigating the use of video, hoping that analyzing embryos over time – rather than checking in on them just once a day – will yield further clues about their quality. Meanwhile, researchers in Greece and Australia have discovered that embryos likely to implant have a distinct set of active genes that are turned off in non-viable embryos. By removing eight to 20 cells from day-5 embryos, the scientists identified the DNA fingerprint of embryos with good odds for implanting and hope to refine the technique so it can be commonly used in IVF labs. “We will still have morphology assessment,” says Dr. Sakkas, referring to the visual evaluation of embryos through a microscope, “but soon there will probably another two or three tests that people will be using routinely that will give us much more information.”
Embryologists emphasize, though, that no matter how skillful they become at picking embryos, quality isn’t all that affects a patient’s chances of getting pregnant. “The transfer is critical,” Dr. Garrisi says, noting that a smooth embryo transfer, without trauma to the uterine lining, gives the embryos the best chance of implanting. The uterine environment – a thick enough lining, for example, and the right interplay of hormones – is important as well; even stellar embryos and a trouble-free transfer won’t ensure success if the embryo doesn’t have a good “home.”
In the end, like so much else about fertility treatments and assisted reproduction, evaluating embryos is at least somewhat an art, not just a science. At Dr. Go’s lab, they’re regularly surprised about which embryos turn into healthy pregnancies. “An embryologist will come into the lab holding a picture of a baby that came from a slowly-developing embryo that was not symmetrical and had a lot of fragments,” she says. “It makes you humble before nature to know that a dreadful-looking embryo can turn into a beautiful baby.”
A version of this article originally appeared in Conceive's 2008 special issue, "The Birds, the Bees, and Modern Medicine."