With a flag hanging outside her house, a crate of Girl Scout cookies in her living room, and a dog named for Disney sensation Miley Cyrus at her feet, Laurie Thompson is about as American as it gets.

The same cannot be said for the 14-week-old twins in her gently protruding belly.

Conceived with a donor's eggs, they are the children of a same-sex couple from Spain who turned to Thompson because paid surrogacy is illegal in their country.

"There's such pride in knowing that I did this for somebody," Thompson says of her experience as a surrogate, which has also included a pregnancy for a married couple from Serbia.

"This is something that is probably hard for most people to do -- with the emotional connection and everything -- and I was able to do it."

She laughs: "And do it again, obviously."

Thompson, who lives in McHenry, Ill., 5 miles from another woman who recently carried a child for a European couple, represents a new twist in global fertility tourism.

In the past five years, would-be parents from as far as Istanbul and Uruguay have turned to healthy young mothers from Illinois to carry their children.

The babies are born U.S. citizens, surrogacy agency officials say, but that's not a primary motivation for the parents, who typically come from European and Latin American countries where surrogacy is illegal or socially unacceptable. The parents have exhausted other options and are willing to pay about $50,000 to $100,000 -- part of which goes to the surrogate -- to have biological children.

No one tracks how many of the estimated 1,400 babies via surrogacy in the U.S. each year are carried for international parents, but one of the larger U.S. agencies, the Center for Surrogate Parenting in Encino, California, estimates that about half of its 104 births in 2010 were for international parents.

In Illinois, which has had one of the most the most surrogacy-friendly laws in the nation, at least two dozen international babies were born to surrogates in 2010, according to a Tribune survey of major agencies. The only other states that explicitly allow contracts for paid surrogacy are Arkansas, California and Massachusetts.

"We're getting inquires from international parents constantly. Because of the referral process, it's skyrocketed," says Zara Griswold, director of Family Source Consultants in Hinsdale, Ill. "We recently got an inquiry from somebody in China."

Casual and confident in jeans and a navy blue hoodie, Thompson, 34, was in good spirits on a recent weekday morning, despite a to-do list that included moving from Wonder Lake to nearby McHenry, Ill., caring for three young daughters, working part time as a bus driver, and finding a new obstetrician.

She said her journey into surrogacy began 17 years ago, she says, when a close friend confided she might not be able to carry a baby.

Thompson's response was immediate: "I would totally do that for you."

Her friend's fertility problem resolved, and Thompson got married and had three children of her own, Avery, 8, Kyrra, 6, and Lacey, 5. When the youngest was born in 2006, Thompson and her husband, Damion, 39, a U.S. Army Reserve unit administrator in Arlington Heights, Ill., knew that their family was complete. Her urge to carry a baby for someone else, however, was still there.

She'd had easy pregnancies with her three daughters, and gestational surrogacy, in which the surrogate's genetic material isn't used, seemed like a good emotional fit.

"I was told that I could be an egg donor, but I can't do that," she says. "I drive a school bus and if a local couple got an egg and I saw this kid walking on my bus that looked like me, it would be really hard."

In late 2008, Thompson told her husband she was interested in surrogacy.

"I wasn't shocked," he recalls. "I just know her, and that's just the way she is. Me being in the Army -- I look at it as no different than what I do. Some people thought I was crazy for re-enlisting during the heat of the Iraq war and Afghanistan war. To me, it's the same thing: She's sacrificing herself to help out other people."

Laurie Thompson had to undergo medical and psychological testing in order to enter into a legally binding surrogacy contract under Illinois law. The law also requires that a surrogate be at least 21, have health insurance, and have given birth to at least one child.

Once Thompson had submitted her surrogacy application to Family Source Consultants, she received three profiles of potential parents. There was a single man from Canada who was already expecting a baby via surrogacy, a married couple in Barrington, Ill., who were still relatively young, and a couple in their 40s from Serbia who were aging out of parenthood after years of unsuccessful fertility treatments.

The Serbians struck Thompson as the ones in the greatest need of her services.

"I want to help them," she said.

The money -- her pay was in the $20,000 to $25,000 range, plus expenses -- wasn't very important to her, she says. Nationality was, but only insofar as it made the Serbian couple's situation more desperate.

In preparation for the Serbian pregnancy, she had to take the drug Lupron, which gave her severe headaches for two weeks. There were numerous doctor's visits and painful progesterone shots that her husband had to administer with a 1 1/2-inch needle, at times on a daily basis. Thompson contracted gestational diabetes at about 26 weeks and to go on a strict diet and check her blood sugar four times a day.

By the time Thompson delivered a healthy baby girl last May, she'd come to realize she preferred international surrogacy. Domestic couples sometimes hover and micromanage, and some surrogates like the attention. Thompson preferred more privacy and autonomy.

As for letting the baby she had carried disappear across the Atlantic, she was ready -- and willing to let the parents dictate the extent of communication in the years to come.

"I went into this with an open mind, saying, 'This isn't my kid, there's nothing biological, I'm pretty much just the incubator,'" Thompson says.

"I never developed an emotional connection with the baby. I mean, obviously, I didn't want anything bad to happen to the baby, but I didn't want to get attached and have that emotional breakdown when the baby was born and it wasn't coming home for me -- and I didn't."

When it was time for the baby's father to say goodbye to Thompson, he followed her to the elevator, saying the same thing over and over again: "Thank you, thank you, thank you, thank you."