Serial Surrogates Have Birthed More Babies for Others Than Themselves.

For some women the excitement of a pregnancy is knowing they are helping someone else become a parent.

Carole Horlock is one of those women -- a surrogate mother who has babies for other couples. She immediately hands over the babies to their parents after they are born.

"I see them hold the baby for the first time, and it's wonderful to see that," Horlock said.

She has enjoyed having babies for other couples so much that she has delivered a jaw-dropping 12 kids in 13 years, meaning the 42-year-old has given birth nearly ever year.

"I've been told that I have got a world record for having the most surrogate babies, but I don't know if this is true," she said. "I've never checked up."

VIDEO: Meet a Serial Surrogate MotherPlay

Horlock said that she didn't set out to become an extreme surrogate. It just sort of happened.

"When I first started being a surrogate I expected to do it once," she said. "I hadn't looked past that. But I enjoyed it so much. Before I actually had given birth to the baby I wanted to do it again."

Anita Brush, another "serial surrogate," said she felt the same way. The 42-year-old Californian has given birth to 11 children, including three grown kids of her own.

She can rattle off all of their names at the drop of a hat: "Taisei, Cole, Connie, Tom, Max, Brendan, Ethan and Jason." And her own kids? "Bryant, Margaret and Rhiannon."

The former day-care worker's unlikely career as a surrogate began 12 years ago, when she was looking for a job that would allow her to spend more time at home with her three young kids.

"I was looking in the newspaper and saw an ad to be a surrogate for infertile couples," Brush said. "I was very intrigued. And I love being pregnant."

After passing a rigorous screening process, which involved psychological tests, medical exams and background checks, Brush joined an agency and quickly became pregnant for a Japanese couple. Brush's son made sure everyone, including his hairdresser, knew all the details about his mom's pregnancy.

Brush remembered her son's explanation: "'Oh, it's a boy but it's not our baby.' And she just kind of pauses as she's cutting his hair and she said, 'It's not your baby?' And he said, 'No, it's Japanese. It's going home to Japan after it's born.'"

Surrogate Mothers Give 'Incredible Gift'

Brush didn't know how she would feel about handing over her first surrogate baby, Taisei, to his parents. But when the moment came Brush said she felt it was "an incredible gift" to be able to hand the newborn over to his parents because "that's the goal. That's what we set out to do."

Surrogates like Brush receive, on average, $25,000 to $30,000 for their services. But there are downsides, including in-vitro fertilization, morning sickness, bed rest, Caesarean sections and stretch marks.

Brush said she's not in it for the money. "Somebody figured it out once, and just in a normal pregnancy like a 10-month pregnancy, it worked out to be about $1.75 an hour."

And if a woman gets all those shots and goes to all those doctor's appointments and she fails to get pregnant, Brush said, she doesn't get paid.

Family Tension

Horlock, who lives in England, has parlayed her extreme surrogate status into additional profit by selling her story to the tabloids. But sometimes the headlines have turned nasty.

"You do it once or twice and you're an angel. You do it time and time again, you're a monster," she said. "If it's a good deed the first time, why doesn't it continue being a good deed?"

It might be because Horlock, unlike Brush, often uses her own eggs. She invites the couple to her house for an at-home insemination -- making a baby, but not the old-fashioned way. The father produces a sample and Horlock inseminates herself.

"It's quite invasive, you know, to have someone else's body fluids inside you," she said. "It's not nice, but it's necessary."

Horlock said her own two children are OK that the babies she has given away are biologically half hers.

"I think these days everybody has half-brothers and -sisters all over the place with remarriage," she said. "And I think as long as you are open and honest about it, they accept it and my children think of it as rather normal now."

But it has also created tension in the family.

"Being pregnant has caused a rift with my father," Horlock said. "The rest of my family are supportive. My father feels I'm giving away his grandchildren."

DNA Test Prompts Refund Offer

In 2004, Horlock got word from a furious father -- a client who said the baby she'd given him was not biologically his. A DNA test revealed that the father was Horlock's boyfriend.

Horlock said she offered the couple a return policy.

"They were very, very angry. I said, you know, 'Whatever you want to do, if you want me to take the baby back, I will do. If you want to keep him and adopt him, I'll support you,' you know, I can't do anything else," she said. "I can't turn the clock back, so I behaved as, I think, as responsibly as I could at the time."

Horlock said the couple asked for their money back and threatened to have her arrested for fraud. But Horlock argued that she and her partner had protected sex. Ultimately, the couple agreed to adopt the child.

An Extended Family

Brush, by contrast, has no genetic link to her surrogate babies. She is always impregnated through in-vitro fertilization using someone else's egg.

In 2000, Brush was implanted with three embryos in hopes that one would take for a gay couple in Ireland. She was surprised with triplets.

But having triplets didn't mean that she got triple the pay. Brush said surrogates get a small stipend for each additional baby.

Because money wasn't her motivation, Brush thinks that she was addicted to being pregnant.

"I loved that people are excited and they'll pat your belly and they'll ask you questions about the pregnancy," she said. "And to feel the baby move and to actually have a life growing inside you."

But not everyone understands.

Brush's daughter Meg Fielder remembered that teachers and friends would comment on her mom's ongoing state of pregnancy.

There were even comments on the Internet, Fielder said, with posters saying things like "what do those poor kids and her husband have to put up with?"

Even so, Fielder said, "it was an amazing experience, and it's done nothing but enhance our lives."

Brush has developed strong loving relationships with most of her surrogate families.

Every year she is invited to now-8-year-old Cole's birthday party.

"I thought it was going to be just a business relationship and a business transaction, you know? I need a baby, you're going to have it for me, and that's it," said Cole's mother, Sarah Case.

Case said she came to realize that Brush wasn't running a business with her surrogacy.

"I knew the first time I talked with her that this was going to be a lifelong friend," Case said. "I knew it."

But a career-ending hysterectomy in 2007 put an end to Brush's time as a surrogate mother.

Horlock, on the other hand, is still at it. She gave birth to triplets in April and says she wants to be a surrogate again.

"I've never done anything important with my career. Some people are scientists, they are working toward a cure for cancer or they made the first airplane," she said. "But you know, at the end of my life, I can look back and say, you know, I made a difference … to these people. And it gives me a great sense of pride that I've done something good with my life."