TUCSON, Ariz.-The evening after I gave birth to my daughter at Tucson Medical Center (TMC), a hospital administrator stopped by our post-delivery room and presented my husband with a bill for about $1,200-the amount we owed after our insurance deductible had been met but before we'd reached our annual maximum out-of-pocket. If we could pay in full that day, the hospital would knock 10 percent off the charge.

Less than half of the women who give birth at TMC receive such a visit. That's because Arizona Health Care Cost Containment System (AHCCCS), the state's public health program, offers free maternity coverage to women in low and lower-middle income classes as well as covering all labor and delivery charges for women in the country illegally. The hospital declined to say what portion of their AHCCCS-covered births involve illegal immigrants but revealed to the Arizona Daily Star in 2007 that around 20 percent of their deliveries are to noncitizen mothers. Considering that illegal immigrants make up between 7 percent and 8 percent of Arizona's total population-and that men in that group significantly out­number women-that accounts for a surprisingly high number. However, it is less surprising once another group of foreign-born mothers who are neither poor nor undocumented are factored into the picture.

Pregnant Mexican women with proper visas who can afford to pay cash for their deliveries are also crossing the border to give birth at TMC. The hospital is one of a few nationwide capitalizing on the cutting-edge practice of birth tourism, targeting specialized maternity packages to Mexican citizens who want to have their babies on U.S. soil.

Though TMC does not specifically advertise U.S. citizenship as a reason for delivering at its hospital, immigration experts say it has always been the main draw for noncitizens-both legal and illegal-who come to the United States to give birth. In a 2009 AP story detailing TMC's birth packages, the Mexican consul general in Tucson, Juan Manuel Calderon Jaimes, found nothing concerning about the practice and said it was nothing new: "Many families of means in Sonora [Mexico] send their wives here to give birth because they have the resources to pay for the services."

But a growing number of U.S. residents are worried about what's happening at hospitals like TMC and how it affects the future of the country. Their alarm is driving the recent push to amend or reinterpret the Constitution so that United States citizenship is no longer automatically conferred upon a person simply because he or she is born here.

According to a recently released study by the Pew Hispanic Center, 37 percent of illegal immigrants in the United States are parents of a citizen child. Even without a citizen in the household, they pose significant costs to states (particularly those that share a border with Mexico) when it comes to healthcare, education, and law enforcement. Once unauthorized residents give birth on U.S. soil, they have access to additional benefits. Mothers and fathers of so-called "anchor babies" are able to apply on behalf of their child for a selection of public programs including Medicaid, Women, Infants, and Children (WIC) subsidies, and food stamps. Should they be apprehended by immigration authorities, they can use the child as justification against deportation and as a reason to request preferred action that will prevent hardship to a U.S.-born citizen. And once the child turns 21, he or she can sponsor his family members' citizenship.

Though Steve Camarota, director of research at the Center for Immigration Studies, confirms that no one can concretely prove that illegal immigrants are intentionally trying to create anchors to the United States by having babies, he says he sees evidence that the parents are well aware of the advantages of giving birth here. He offers detailed statistics by state, noting, for example, that 40 percent of the unauthorized residents in Texas and California utilize food assistance and that a third of those in New York use Medicaid, most often on behalf of a citizen child. Says Camarota, "It is clear that a very large fraction of the illegal population with U.S.-born children learn to navigate certain welfare programs like Medicaid, WIC, and preschool lunch. And it's clear that a significant body of knowledge in regards to that is shared among them on how to sign their children up."

With states like California and Arizona facing crushing budget shortfalls, it's not surprising, says Camarota, that people are becoming upset over birthright citizenship. "So after [illegal immigrants] break the law coming here, they have a baby and get to benefit further by getting a green card and permanent residency? There's a lot not to like there." As for the wealthy, visa-wielding moms-to-be, he sums up the general objection succinctly: "It's the same as buying U.S. citizenship and turns something we should prize and respect into a game."

Eileen Walker, a labor and delivery nurse at Thunderbird Medical Center in Glendale, Ariz., agrees with Camarota's assessment and says in her work she sees illegal immigrants abusing emergency treatment laws and the AHCCCS program. "AHCCCS won't cover an illegal patient's doctor's visit, but the hospital is different. Anyone who walks into OB Triage claiming a health problem, we have to provide care. If they come in and say they're having headaches or have a cold or flu symptoms, we have to provide care." She says pregnant noncitizens understand that they can use emergency treatment as regular maternity care. "They know the right things to say and they know how to manipulate the system. They'll say, 'I'm not feeling my baby move,' because it is a guaranteed way to get the doctor to order an ultrasound. So they can get every benefit-top-of-the-line sonograms, epidurals, all the care a patient with insurance or who is paying out of pocket has-for free."

Some illegal immigrants fail to complete the paperwork that allows the hospital to get reimbursed by the state for its services, says Walker. "They'll get the care they came for and then just disappear, and we'll look around and say, 'Where did they go?' They leave and we find the AHCCCS application in the room," says Walker. "We eat those costs." As a result, she says, employees of Thunderbird have seen a drastic reduction in their own benefits as the hospital tries to cut expenses without resorting to layoffs.

Experience like Walker's and research like Camarota's are what's driving legislators who say it is time for the United States to reconsider its practice of granting citizenship to everyone born here. Among those who support hearings on the issue are Sens. Lindsey Graham, R-S.C., Jon Kyl, R-Ariz., and Mitch McConnell, R-Ky., as well as House Minority Leader John Boehner of Ohio. Graham is particularly vehement, calling birthright citizenship "a mistake" on Fox News in July and announcing possible plans to introduce a constitutional amendment to reverse it.

The concept of citizenship by birthright has its roots in past injustices. When the Supreme Court ruled in the 1857 Dred Scott case that blacks were not citizens, Congress responded by passing a statute that conferred citizenship by birth. After the Civil War, citizenship for freed slaves received constitutional grounding in 1868 with the 14th Amendment. It states, "All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside." The frontline of the objection against anchor babies is that clause, "subject to the jurisdiction thereof." Those who believe that the children of illegal immigrants shouldn't be considered citizens argue that the 14th Amendment was never intended to apply to them because their parents are not U.S. citizens nor here with U.S. authorization, and therefore are not subject to its jurisdiction.

Recent polls show Americans split about 50-50 on whether birthright citizenship should be repealed-though in border states like Arizona support for the idea is stronger, with two-thirds favoring it. But even someone like Camarota-whose career is researching illegal immigration and publicizing the problems it creates-is hesitant to endorse such a constitutional change.

On the one hand, he says he agrees with Republican leaders who point out that the United States is one of the only industrialized democracies to give citizenship to everyone born within its borders. And he understands the frustration of those who feel that birthright citizenship makes it extremely difficult to solve the problems of illegal immigration, as groups opposed to enforcement can claim that it divides families. "Politically, it creates a much different environment in which to have the debate. One of the chief arguments for granting amnesty to unauthorized residents is that they have all these citizen children and we shouldn't do harm to citizen children," says Camarota. "The advocacy groups make that argument all the time and you get [President] Obama saying that we're tearing babies from their mothers' breasts by trying to enforce the law. Of course the child can always go with the parents so we're not really dividing families, but it allows that narrative to be constructed. So it matters enormously in the immigration debate and it greatly complicates our efforts."

Camarota says that the odds against changing the law are steep. "It'll be a tough, nasty political battle that will focus on children. If you're pro-enforcement, that's not what you want," he says. Even if Congress passed a law, it would by no means signal the end of the fight: "You'd still have an ambiguous outcome because it would have to wind its way through the courts for years. Then if you'd wanted to change it you'd have to get a constitutional amendment. To my mind it's just not where we should put our political efforts."