The science of freezing and preserving human embryos has made it possible for once-infertile couples to bear children.

It's cheaper, and often easier, for the recipient couple than most other options.

But where science opens a door, ethics, religion and fear often make society reluctant to explore.

One-week-old Austin hiccups and coos in his mother’s arms.

His parents consider him a miracle of reproductive biology and of generosity.

“It’s been amazing,” says the baby’s mother, Taren, sobbing. “It’s kind of a dream come true for me.”

She and her husband Ernest, who prefer not to publicize their last names, have infertility problems.

Working with a Dallas infertility specialist, they tried several options, but nothing resulted in a successful pregnancy.

Then – as one of their last resorts – the Frisco couple considered using a donated embryo. One fertilized - and frozen in time – by another couple.

“I think, in a way, we’re doing a service to another family that has done in vitro fertilization,” says new father, Ernest.

They approached the process from a Christian perspective, and consider human life to begin at conception.

“We prayed about it a lot,” adds Taren.

The growing demand for fertility assistance in the United States, and the success of in-vitro fertilization, has made embryo donation a more pressing problem now than ever.

Almost half a million human embryos are currently frozen at fertility clinics nationwide.

Many will be used to produce babies for the couples in treatment.

But the destiny of the rest remains in limbo because many couples are reluctant to make the difficult decision about their ultimate use - to be destroyed for research or donated to another family.

“When push comes to shove, it’s sometimes difficult for those couples,” says Dr. Sam Chantilis, a fertility specialist at Presbyterian Hospital of Dallas. “To think, 'gosh, that’s my baby being given up for adoption.'”

Whereas sperm and egg donation has become rather common in the U.S., often tendered by a third-party tissue bank, embryo donation is conducted on a case-by-case basis, and is still considered rare.

Each fertilized embryo is frozen in a tiny plastic capsule. While a single fertility clinic may have thousands at any given time, only some lead to viable pregnancies, and only a tiny fraction of those left over become available for other couples.

At the Center for Assisted Reproduction in Bedford, Dr. Kevin Doody has several thousand frozen embryos stored in cast-iron tanks and coolers.

Thick white liquid nitrogen gas spills out of the containers when opened. The tiny vials are kept separate in small racks coated with white frost. Doody councils his patients daily on the three options for surplus embryos – they can be destroyed, donated to research, or donated to another couple.

“Given the three options,” he says, “the majority of couples actually desire to discard their embryos or donate them to research, rather than for reproductive purposes.”

While Doody has been performing the procedure for ten years, he has almost no surplus frozen embryos available. The demand far exceeds the supply, and each one donated is taken almost immediately.

Fertility specialists say most couples grapple with the decision.

“I think the main issue is, do you want someone else to raise your genetic embryo?” says Dr. Chantilis. “Do you want another couple to raise your child?”

Toni Crawford and her husband Michael recently had twin boys using in-vitro fertilization. They had three extra fertilized embryos after the procedure, which they did not plan to use.

“To me, you know, we had the twins, and there were these three little souls,” says Crawford, "waiting in a dish, and I said ‘take the jump.'"

She and her husband may never know where their embryos end up.

In Texas, the procedure is not considered adoption, although some out-of-state adoption agencies facilitate the transfer.

So, donating parents have no legal rights to any resulting offspring.

“No regrets whatsoever” says Crawford “wonders, but no regrets.”

At the Bedford clinic, about 10 percent of the excess embryos are donated to other families. But that percentage is high compared to the nationwide average of about 1 percent.

“I think it’s been slow to catch on,” says Dr. Doody, “and frankly, I’m a bit mystified myself as to the reason behind that.”

What science has made possible, state law barely recognizes, and common culture is seemingly slow to consider.

But for couples like Taren and Ernest, the opportunity to meet Austin has changed their family, and their world.

“What a miracle,” says Taren as she holds her newborn baby, “to be able to experience pregnancy, which is something I didn’t want to miss out on.” She and Ernest have an open arrangement with Austin’s biological family in Delaware. They plan to keep in touch with the parents and even have photos of Austin’s biological siblings.

“What if there was an amazing human being left over?” asks Ernest.

E-mail jbrady@wfaa.com.