"To see [parents'] faces when their sweet precious baby came out was priceless," said Colleen, 30, who gave birth to another couple's child last year.
In addition to nine months of pregnancy, gestational surrogacy can require a several-months-long process involving embryo transfers, in-vitro fertilization, medications and doctor's visits before finally conceiving an embryo. For Colleen and other surrogates, this long-term commitment is a labor of love.
"The labor, the pain, it was all worth it," said Colleen, who has two children of her own and lives in California with her husband, Duane.
It was also a financial boost. Duane earns about $30,000 a year in the Army. Colleen made $30,000 for carrying a surrogate child while Duane was serving in Iraq.
"It truly was a way for me to earn some kind of income, but also bless the family," she said, adding it gave her the freedom to stay at home with her kids. "I mean, you have to have your heart in it to be a surrogate mother."
There are an estimated 1,000 surrogate pregnancies each year in the United States. Surrogate agencies say 15 to 20 percent of surrogate babies nationwide are born to military wives -- even though the military makes up less than 1 percent of the U.S. population.
Melissa Brisman, who runs Reproductive Possibilities, a surrogacy agency in Montvale, N.J., that matches intended parents with gestational surrogates, said military wives often make perfect surrogates.
"They move around a lot, so they really can't get their teeth into a career, and if they want to contribute to society and do something useful, it's a good use of their time," said Brisman, whose agency employs about 20 military surrogate mothers out of more than 200. "A lot of them are just strong family people...and what a better thing to do for somebody than have a baby for somebody who can't."
Surrogacy has long been a hot topic in military circles. It was featured in the pilot episode of the Lifetime series "Army Wives," in which the show's protagonist secretly becomes a surrogate to earn money to get her family out of debt.
It was a secret, in part, because taxpayers often help pay part of the bill for military surrogacies.
Government health insurance, provided by the Tricare program for military families, covers pre-natal and delivery costs, but as a policy, does not cover surrogacy.
Colleen says Tricare did not question her surrogate pregnancy and she did not notify the insurance provider. She says she does not think there is anything wrong with Tricare covering some of her pregnancy costs.
"[My husband] worked for that benefit...he was out there, fighting, doing his work, and that is a benefit that is awarded to us," she argues. "Pregnancy is covered, under the benefit of your medical care. So I was just using a benefit that was awarded to me."
The cost of surrogacy is usually about $100,000, but Tricare ends up paying only a small portion of that -- $5,000 to $10,000. It does not pay the in-vitro fertilization costs, for instance.
In a statement, Tricare said it "has a right to recover funds" from surrogate mothers. So far, they rarely do.