Matt and Andrea Thomas spotted each other walking across campus at Texas A&M University, struck up a conversation, and fell in love. They married after graduation and found jobs in Austin, Texas-Matt as an engineer and Andrea as a teacher. Having children seemed like the next step in their lives together.

The next step turned out to be a six-year journey, the first two of which they spent trying to conceive a child naturally. Not long after their first visit to a fertility doctor, they found out that a specialized form of in vitro fertilization was the only procedure that would give them a chance to conceive. Their options were clear, but their decision was painstaking.

Over the next four years, the Thomases enlisted the prayer and counsel of what seemed like everyone they knew. Their pastor at All Saints Presbyterian Church prayed for them from the pulpit. Sunday school children would pass by Mrs. Thomas at church and say, "I'm praying for God to give you a baby."

What the Thomases really needed was wisdom. In the spring of 2000, they went to meet with the elders of their church. Sitting with the elders around a large conference table in an office building in downtown Austin, Mr. Thomas opened his heart.

"I have a desire, and I think it's a godly one, to see a daughter who has my wife's bright blue eyes," Mr. Thomas explained to the elders, who agreed his desire was godly. But the Thomases also desired to pursue God's will in every detail of the IVF procedure, one aspect of which made them uncomfortable. The Thomases' doctor recommended that he fertilize as many as 20 of Mrs. Thomas' eggs, place a few in her uterus, then cryogenically freeze the rest for later use, in case the first attempt failed. The chances the embryos would survive the thawing process were as low as 50 percent.

"It's just a little weird to think about freezing your children and thawing them out," Mr. Thomas said. He and his wife decided they would only fertilize as many eggs as they were willing to implant immediately. They fertilized five eggs. Three of them developed into embryos, and two of them thrived in Mrs. Thomas' uterus. Emma and Jacob Thomas were born Feb. 2, 2001.

The Thomases' decision not to fertilize extra embryos went against what had been the accepted practice of IVF clinics for 15 years. In 2002, a survey by the Society for Assisted Reproductive Technology estimated that 400,000 embryos remained frozen in IVF clinics across the country. Frozen eggs in the United States far outnumber those in other countries such as Australia and New Zealand, which had about 71,200 combined in 2000. Great Britain estimated in 1996 that it had 52,000 eggs in frozen storage.

Unlike the Thomases, many U.S. doctors, politicians, parents, and Protestant clergy members never thought twice about the practice of embryo freezing-until 1998. That year, Dr. James Thomson at the University of Wisconsin announced he had harvested the first embryonic stem cells from "leftover" IVF embryos. Scientists predicted embryonic stem-cell research would lead to miraculous cures for diseases, thanks to the parents who had donated their test-tube babies' frozen siblings to science.

As news of the new embryonic science spread, pro-life activists protested. In 2001, pro-lifers won a major victory when President Bush put a moratorium on any further embryo destruction by researchers who receive federal funding. Since then, the pro-life movement's defense of frozen embryos has weakened as members of its ranks struggled with the futility of saving 400,000 frozen children. A bill to ease Mr. Bush's restrictions on embryo destruction pulled 50 Republican votes when it passed in the House of Representatives this summer. More recently, Senate Majority Leader Bill Frist, who traditionally votes pro-life, lent his support to the bill. For Mr. Frist and others, the attraction of embryonic stem-cell research is that it answers a question that has stymied evangelicals for over a decade: If parents don't want their own frozen embryos, and scientists can't have them, what is to be done with them?

In 1978, the world's first test-tube baby, Louise Brown, was born in Oldham, England. Since then, most countries have established regulations governing assisted reproductive technology (ART). ART includes IVF, the most common of several fertility treatments that involve doctors handling eggs and sperm. Whether liberal or conservative, most countries have laws stating who can undergo in vitro fertilization, how it should be performed, and what happens to unused embryos.

Some countries give couples, clinics, and scientists license to do almost anything they want with embryos. Great Britain's Human Fertilisation and Embryology Authority hands out licenses for human cloning and arranges egg swaps between infertile couples and young, fertile women. Italy, in contrast, passed a law in 2003 banning embryo freezing and limiting the number of embryos that can be fertilized during IVF. Earlier this year, that law withstood a public referendum to repeal portions of it.

The United States has no law governing IVF other than general medical licensure and health requirements. The government keeps statistics on IVF success rates, but clinic participation is voluntary. Only one state, Louisiana, has a statute that regulates the storage of IVF embryos and defines their legal status.

The United States' refusal to regulate IVF has close ties to the importance Americans place on privacy. In his book Brave New Families: Biblical Ethics and Reproductive Technologies, Biola University professor Scott Rae traces how the Supreme Court secured "procreative liberty" in the United States with cases like Eisenstadt v. Baird, a case over an unmarried couple's right to use contraceptives.

In the majority opinion of that case, Justice William Brennan wrote: "If the right of privacy means anything, it is the right of the individual, married or single, to be free from unwarranted government intrusion into matters so fundamentally affecting a person as the decision whether to bear or beget a child." In other words, reproduction is none of the government's business. It is, however, the business of the doctors who perform IVF-big business.

According to the American Society of Reproductive Medicine, the average cost of one round of IVF in the United States is $12,400, which health insurance may or may not cover. Retrieving eggs from a woman's ovaries can account for as much as half of the cost-and most of the inconvenience-of IVF. Before egg retrieval, a woman has to take expensive medicine to make her ovaries produce more mature eggs than normal. The drugs can cause side effects like bloating, nausea, diarrhea, and sometimes severe enlargement of the ovaries. Then a doctor retrieves the eggs from the woman's ovary with a small needle, usually while the woman is sedated.

The U.S. success rates for IVF hover around 30 percent, so clinics counsel their patients to prepare for multiple rounds of treatment before conceiving. Almost half of the women who underwent IVF in 2002 had had the treatment before, according to the Centers for Disease Control.

Given those facts, it's easy to see why embryo freezing became so widespread. By retrieving enough eggs for three or four cycles at once, couples could greatly reduce the cost and discomfort of future cycles. Doctors had to fertilize the eggs first because the freezing process typically destroyed unfertilized eggs. Only embryos could survive freezing and thawing.

By the late 1980s, embryo freezing had become an integral part of all assisted reproductive technology, not just IVF. Doctors took for granted that couples like Greg and Kathy May of Irvine, Calif., wanted to freeze their eggs.

After failing to conceive a second child following the birth of their son Bryan in 1987, the Mays chose to undergo gamete intrafallopian transfer (GIFT). GIFT is similar to IVF, but instead of fertilizing the eggs in a dish, the doctors implanted the egg and sperm separately into the fallopian tube. As in IVF, Mrs. May underwent ovarian stimulation and egg retrieval. She and Greg even drove an hour and a half to Mexico to buy the necessary drugs at a lower price.

Doctors harvested nine eggs and implanted four. The other five they fertilized in vitro and froze. Mr. May said he looked at the frozen embryos as a kind of "insurance policy," in case Mrs. May did not get pregnant on the first try.

"That was a lot less expensive than having to go to Mexico," he said. The first attempt succeeded. On Dec. 30, 1992, Mrs. May gave birth to triplets: Melissa, Stephanie, and Doug.

The years following the triplets' births are a blur of excitement in Mrs. May's memory. Keeping up with a grade-schooler and three babies left little time to think about the five leftover embryos frozen at the clinic at Saddleback Memorial Hospital. Once a year, the Mays paid the clinic's storage fee, not yet ready to decide what to do with the embryos. A few years after the triplets' birth, they decided to give them up for adoption.

What the Mays lacked, at least early on, was spiritual guidance. When the Mays first discussed their infertility with their friends from church and Bible study, they received encouragement. "They all said, 'God has given the doctors this wisdom. You should try it . . . God's in total control,'" Mrs. May said. The topic of embryo freezing never came up. The only literature the Mays read before the procedure was provided by the clinic.

Protestant churches have not only refrained from establishing doctrine about in vitro fertilization, but have shied away from public discussions of the topic. The Roman Catholic Church, in contrast, hasn't been silent.

The Vatican's Congregation for Doctrine of the Faith, headed by then-Cardinal Joseph Ratzinger, now Pope Benedict, published a teaching called the Donum Vitae, or "Gift of Life." The Donum Vitae enumerated the Catholic case against in vitro fertilization, embryo freezing, and research on embryos conceived during in vitro fertilization. It affirmed, however, that all embryos, including those created in vitro, must be respected from the moment of conception.

"Outside Catholic circles, I think, the problem of the disposition of embryos has been ignored for some time because it's uncomfortable," said Biola's Scott Rae. The Thomases also noted the lack of Protestant writings on the subject. "We felt so alone," Mrs. Thomas said. "Nobody had written anything concise."

Mr. Rae, himself an evangelical , wrote in his book in 1996 that he recommended almost exclusively Catholic authors when asked for theological readings on reproductive technology. "Those few evangelical sources that did exist tended to treat the subject simplistically," he wrote.

If non-Catholic churchgoers have been indifferent, they mirror public indifference. The public viewed the embryos as property, and couples saw no need to consult their pastors over how to dispose of their property. The Mays weren't indifferent to their embryos; they said they would never have simply destroyed them. At the same time, they said their eventual decision to give the embryos up for adoption came easily.

"We didn't really think of them as our children," Mrs. May said. "It was just a baby for somebody else."

Evangelicals started to realize the consequences of their indifference around the turn of the millennium. Scientists had already made strides treating diseases with stem-cell transplants. In the transplants, adult stem cells (which can be any stem cell post-birth) act as factories for creating new, healthy cells that heal tissue damage from disease or injury.

Many scientists had come to believe embryonic stem cells could similarly cure even more devastating diseases because, unlike specialized adult stem cells, they had the potential to produce almost all the tissue in the body. Harvesting stem cells from an embryo destroys it.

President Bush's 2001 policy limited federal funding for research on embryonic stem cells to those already harvested. No federal funding, he stated, could go toward further stem-cell derivation and embryo destruction.

Since then, scientists have bemoaned the quality of embryonic stem cells available for research. They have enlisted people suffering from devastating diseases-Parkinson's, Alzheimer's, paralysis-to pressure every level of government for more support for embryonic stem-cell research. Their arguments assume that most parents do not want their frozen embryos. They portray embryonic stem-cell research as the lesser of two evils when compared to throwing unwanted embryos in the trash.

"Embryonic stem-cell research need not increase the number of embryos destroyed," Rep. Sherrod Brown (D-Ohio) argued during House debate last summer. "Instead, it decreases the number of embryos destroyed in vain."

In reality, few parents have expressed a willingness to donate their frozen embryos to research. The 2002 census of frozen embryos found that only 2.8 percent of the estimated 400,000 were being stored for future use in research. About 65 percent of those embryos could be expected to survive the freezing and thawing processes. The study noted scientists usually make many unsuccessful attempts before deriving a usable line of embryonic stem cells. Therefore, the embryos currently stored for research would likely produce a mere 275 cell lines.

Ironically, researchers at the forefront of the field have already lost interest in using frozen embryos as a source of stem cells. They would rather make their own embryos through cloning. The appeal of cloning lies in the fact that a person's body would automatically accept stem cells taken from clones of themselves. The use of donor stem cells would risk rejection, as is the case in organ transplants.

"There are methods of deriving embryonic stem cells from cloned embryos that could be used to study and, in time, to treat human disease," Ian Wilmut, Great Britain's best-known embryo researcher, told reporters in late August. "Let's get on with this, for the sake of thousands of patients."

So where does that leave 400,000 unborn, frozen embryos?

In March 2004, the President's Council on Bioethics released a report noting the lack of uniform regulations and standards for assisted reproduction. The report listed some policy options for regulating IVF and similar procedures, but stopped short of endorsing any one method of government oversight of the field.