Claire and Drew Nielsen weren't the least bit downhearted as they left Abbott Northwestern Hospital in south Minneapolis two days after she gave birth to 7-pound twin girls, even though neither of the newborns was with them.

They never expected to bring the babies home.

"I knew the twins were where they belonged, with their parents who already loved them so much," Claire Nielsen said.

She had served as a gestational surrogate, carrying the babies for a same-sex California couple. It was something she had been contemplating since her second child arrived.

"We had our girl and our boy; our family was complete," she said. "I thought surrogacy would be a cool thing. To allow a same-sex family have a bio child interested me."

A small but growing number of would-be parents are using gestational surrogacy to build families. Advances in reproductive technology have allowed the procedure to gain ground, and the celebrity embrace of the practice — with Hollywood couples increasingly forthcoming about their reliance on a surrogate — has lifted it out of the shadows.

Nielsen, 27, has no biological link to the twins, who were born in December. They were created with sperm from each man and eggs from an anonymous donor. That's the difference between gestational surrogacy and traditional surrogacy, which uses an egg from the carrier, making her the baby's biological mother.

"I birthed them, but they were never mine," Nielsen said.

When she started doing research on surrogacy, she discovered Growing Generations. Based in Los Angeles, it calls itself the largest surrogacy and egg donation agency in the country. After a phone interview, the agency flew the Maple Grove couple to California for medical and psychological testing.

"You do this as a couple," said Drew, 28, a Web designer. "They wanted to make sure the relationship is solid."

The agency requires its surrogates to have given birth, with uncomplicated labor and deliveries. Its scrutiny extended to the couple's finances, and both had to pass a criminal-background check.

Once approved, the Nielsens were matched with what's known in surrogacy circles as the "intended parents." The two couples met over a meal.

"We said we were going on a double blind date-slash-job interview," Claire said.

Tim Floreen, 41, and Duncan Kerr, 51, of San Francisco felt an immediate connection with the Nielsens.

"We just clicked," Floreen said. "I remember Claire said, 'I look at this as the most important baby-sitting job I'll ever do.' We felt like we would be in good hands."

To prepare for the pregnancy, Nielsen gave herself daily shots in the abdomen for four weeks. After the donor eggs were combined with the sperm from the parents, the Nielsens again flew to Los Angeles, where two embryos were transferred into Claire's uterus as her husband held her hand and the prospective fathers watched.

"We knew they were two girls, and we knew one was connected to each parent," she recalled. "I crossed my fingers and said, 'Grab on.' "

'The best-case scenario'

A blood test 12 days later confirmed that she was pregnant, but everyone had to wait another two weeks after that before an ultrasound showed that she was carrying twins.

"It was the best-case scenario," she said. "It was really going to happen for these guys."

During the first trimester, Nielsen's husband gave her daily shots to help the pregnancy hold.

"These shots were painful," she said. "It goes in slow into the hip muscle. Every place the needle went in made a lump, and pretty soon there isn't anyplace that isn't tender."

On difficult days, Nielsen found support on a private Facebook page set up by the agency. She developed an online friendship with Brooke Schroht, a gestational surrogate in Owatonna, Minn.

Schroht, a 27-year-old married mother of three, has been public about the circumstances of the pregnancy.

"This is a small town, so I'm well-known. The story travels fast," she said. "I told my church. I'm trying to open some eyes to this. Love is love. Everyone deserves to have a family and carry on the legacy of their genes and their name."

According to the American Society for Reproductive Medicine, 1,939 babies were born to gestational carriers in 2013, up from 738 in 2004, the first year records were kept.

"It's a new medical avenue for people to have children," said Linda Hammer Burns, a psychologist at the University of Minnesota Medical School who has counseled infertile couples for decades and has studied surrogates. "Demand for this will only rise."

Surrogacy is often a speedier route to parenthood than adoption. It typically takes 12 to 18 months; the wait to adopt can be significantly longer. And while some parents seek a gestational carrier due to infertility, many, as in Nielsen's case, are same-sex couples.

"This is a big cultural transition," said Ellen Lewin, an anthropology professor at the University of Iowa who researches gay family life. "DNA is a big deal in our culture. People have ideas about how it forms kinship. In surrogacy, the intended parents want a biological connection to the baby."

Surrogacy doesn't come cheap. With medical, travel and legal expenses, it can top $100,000, according to Growing Generations. The agency indicates its Minnesota surrogates receive $25,000, with an additional $5,000 for delivering a second baby and $5,000 in "additional fees and allowances." The Nielsens confirmed that was consistent with the compensation Claire received.

"It's not a get-rich-quick scheme," she said. "You sacrifice a lot to do this."

Some states have laws forbidding gestational surrogacy, but Minnesota does not.

Jennifer Lahl, founder and president of the California-based Center for Bioethics and Culture, would like to see all forms of payments for surrogacy outlawed.

"The minute money enters in, you literally pay women to assume health risks to make a baby," she said.

Money aside, Lahl has doubts about the process itself. "With surrogacy, we tell mothers, 'Do not bond; do not attach.' What does that do to the psyche of the women and the newborn? We haven't studied the impact of this."

A group effort

As the pregnancy progressed, the Nielsens and the fathers-to-be connected with weekly phone updates, daily texts and photos of Claire's expanding midsection.

"When we started this process, we were focused on the end result, but the experience of going through the pregnancy was a bonus," Floreen said.

He and Kerr arrived in Minnesota three weeks before the due date. When the time finally came, labor was short. Ada arrived first, and was handed to Kerr.

"The baby was bright red and screaming," Nielsen said. "I had done it. I delivered a big, fat, healthy baby. I was crying, Drew was crying, the parents were crying. It was magic. And there was still a whole 'nother baby to be born."

Seven minutes later, Lucy was placed in Floreen's arms. "Instinct takes over; you feel this bond form instantly," he said. "It took me by surprise in the best possible way."

For Drew Nielsen, being in the delivery room was different this time. "Before, I was there for my wife and our kid," he said. "This time I was there for Claire, not the babies. They had people to take care of them."

Floreen said they plan to be frank with their daughters about their conception and birth. "We want them to be proud of their family background. We want them to know their whole story, so they'll see how loved and wanted they were."

The Nielsens have begun to talk about whether to pursue the process again.

"My agency lets you be a surrogate until you're 40, so we have time," Claire said. "The recovery went well, and I had no lasting effects, and no regrets. I've birthed four children and created an entire family."

Kevyn Burger is a freelance writer and newscaster at