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Last year the American Society for Reproductive Medicine drafted guidelines squarely aimed at Silber, one of the few if only physicians in the country offering ovarian-tissue freezing for otherwise healthy women. "Due to the present potential risk-to-benefit ratio, ovarian tissue cryo-preservation should not be currently either marketed or offered as a means to defer reproductive aging," warned the ASRM missive.
The Center for Bioethics at the University of Pennsylvania in Philadelphia labels ovarian-tissue freezing as "very experimental" and recommends it only as a last-resort measure. "It's one thing to offer this to a woman with cancer who may have no other alternatives," posits the center's director, Arthur Caplan. "But it's hard to see this as ethically sound for women who choose it for lifestyle reasons, especially if these eggs create fetuses prone to involuntary abortion or children with a high rate of birth defects."
Still, Silber forges ahead. "The way I see it, this is every bit as revolutionary as the birth-control pill," he says. "Let's face it, there's just too much advantage nowadays for women to concentrate on education and a career, and they don't want to hear a doctor or medical association telling them to hurry up and get pregnant. So what's the solution? Simple, it's technology."
A century ago American women lived to an average age of 48.3 years. Now, thanks to diet and medicine, the average woman in the United States is alive to blow out the candles on her 78th birthday. But has the female biological clock also increased alongside life expectancy? No. Today's female shares the same ovaries as her Stone Age sisters did 10,000 years ago.
Take the Hadzi bushmen in Africa, for example. A tribe of hunter-gatherers, the Hadzi live much the same way as their ancestors did millennia before. By day, the Hadzi seek whatever food and water they can find along the Tanzanian plains. By night, they sleep under the open sky. Few members of the tribe live past 40 and nearly all the females have children by their late teenage years. Dr. Silber visited the Hadzi a couple years back and, when he tried to explain his field of medicine, the Hadzi greeted him with blank stares. Their language doesn't even have a word for infertility. In the Hadzi world, there is no such thing.
Of course, it's a different matter entirely in the developed world. "Two generations ago almost all women in the U.S. and Europe were having babies in their teens or early 20s," notes Silber. "Today, many women think they're getting an early start when they try to get pregnant at age 26. But by then one in ten women are infertile. By age 35, one in four can't become pregnant."
Thankfully, says Silber, today an answer exists to perhaps the biggest riddle facing women of reproductive age. A so-called "antral-follicle count," or AFC, can gauge with relative accuracy each woman's unique biological clock, taking into account the number of mature eggs developing in her ovaries at any given time. These mature eggs correspond directly to the total number of eggs in a woman's ovarian reserve, allowing physicians to determine when she's likely to become infertile.
The problem with this procedure, concedes Silber, is that most gynecologists are wholly ignorant of its existence. "Ideas don't spread in this industry unless some drug manufacturer decides it can make a lot of money on something," he grouses. "And right now there's no money to be made with the AFC test. It's a simple ultrasound procedure and, unfortunately, doctors aren't using it."
For Silber, the follicle count serves as a guide for the dozens of female clients who've approached him with the hope he can prolong their fertility. Healthy women with high antral-follicle counts or patients like Ashley Perkins who are about to undergo chemotherapy might best be treated through ovarian-tissue freezing. Other women may choose egg freezing, in which they're prescribed hormones to stimulate the ovaries into dropping multiple eggs during ovulation. Silber and his staff retrieve the eggs vaginally without surgery and freeze them in much the same manner as ovarian tissue. When the patient is ready to have a baby, the frozen eggs are inseminated via in vitro fertilization and inserted back through the vagina.
"It's kind of like asking which form of birth control is better: the Pill or an IUD?" reflects Silber. "With ovarian-tissue freezing, it's a couple outpatient surgeries and the woman can become pregnant naturally. To me, that seems easy. But maybe she doesn't want surgery. In that case we can freeze her eggs and she gets pregnant in a petri dish. Either way, the end result is a baby."
Unlike human embryos, which scientists have successfully frozen for decades, it's only been in recent years that eggs and ovarian tissue have survived freezing through a process called vitrification. The technique requires the egg to be bathed in an antifreeze solution that repels ice crystals during a near instantaneous decent into deep freeze. Thus far, babies born from eggs frozen through vitrification have shown no side-effects, but scientists caution that further data is needed.
"The question everyone wants to know is, how good will these eggs and tissue be twenty years down the road? And the answer to that, we just don't know," says Dr. David Battaglia, a noted fertility specialist with the Oregon Health & Science University. "Just about 300 children have been born worldwide as a result of egg freezing. And far fewer than that just three or four have been born from ovarian-tissue freezing. So we're really at the very infancy of this research."