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By freezing embryos, couples try to utilize fertility while delaying parenthood

Over the past 30 years, millions of IVF babies have been born, and that made for a very broad database. (That sets embryo freezing apart from the relatively new and unproven process of egg freezing, which doesn't have enough of a track record for me to trust it with my future family.)

There's not enough space here to explain, or even refer to, all the reading I did. But, for example, in "100 Questions and Answers About Infertility," Michael DiMattina and John D. Gordon of Dominion Fertility in Arlington described the research on IVF children as "extremely reassuring." The doctors note a possible 2 percentage-point elevation of risk of birth defects among IVF babies. But they, like Carmen Sapienza, a geneticist at Temple University School of Medicine, argue that these excess defects may occur because many couples seeking treatment -- those undergoing Desperation IVF -- may have secondary problems associated with infertility. Young, fertile couples could be expected to have a lower risk.

What does the freezing process do to the embryos? Again, I was reassured by the research. For example, a 2008 study by American Society for Reproductive Medicine reported higher birth weights and lower stillborn rates for frozen-embryo babies than fresh-embryo babies.

Furthermore, freezing technology keeps improving. Drew Tortoriello, a physician with the Sher Institute for Reproductive Medicine in New York, introduced us to vitrification, an ultra-rapid process that prevents the formation of damaging ice crystals in the embryo, which had been a danger in older, slower freezing methods. He reported a successful thaw rate of better than 95 percent.

According to the Society for Assisted Reproductive Technology (http://www.sart.org), which collects data from hundreds of IVF clinics nationwide, when women younger than 35 underwent IVF with fresh embryos, 47 percent resulted in live births; with thawed embryos, the rate was 35 percent. Initially, those success rates did not sound that high. But the numbers referred to a single cycle; most couples, as I said earlier, produce several embryos during IVF, and if the first implantation is unsuccessful, they try again, and the cumulative success rate is much higher.

The most relevant statistics appeared to come from couples who used egg donors to create embryos. Like those couples, my uterus might be 40 years old when it receives an embryo created with eggs from a 30-year-old -- that is, from me. Tortoriello told me that his clinic's 2008 success rate for egg-donor IVF was 68 percent per cycle for a fresh transfer, and 38 percent for frozen embryos. He attributed that difference largely to the fact that "the best embryos tend to get transferred initially with the first, fresh transfer." A woman doing Preservation IVF, he said, "would probably be closer to the fresh donor egg IVF success rate."

Next there was the question of storing our blastocyst embryos.

The clinic would handle the vitrification process. Then the embryos might be transferred to a long-term storage facility, whose chief responsibility is to monitor the temperature of the liquid nitrogen tanks.

From the beginning, I'd been worried about the drugs involved in IVF. Typically, women undergoing treatment get repeated hormone shots that stimulate ovaries to produce numerous eggs, so the clinic can harvest a large number in one or two menstrual cycles. Besides being taxing and time-consuming, the drug injections can cause PMS-type symptoms, pain, missed work. They scared me.

But I learned I had two other options: natural and minimal-stimulation (or mini) IVF.

No fertility drugs are used in natural IVF; a doctor retrieves the single egg that a woman naturally produces each month. Minimal-stimulation IVF involves low-dosage pills or a small number of shots to stimulate the production of just a few extra eggs. Since my young age indicated that I could expect to produce a healthy egg every month, I liked both these choices. The number of side effects would be greatly reduced, and I just felt better about creating our future child with fewer drugs in my body.

A three-cycle package of minimal-stimulation IVF or natural IVF costs about $11,000. Pre-screening evaluations and blood tests cost about $2,000. The annual storage fee for the frozen embryos is $300 to $500 per year, and it costs about $1,000 to $2,000 each time embryos are transferred into the uterus.


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