"Do you want to have your baby in the United States?"
That query flashes on two digital billboards south of the border as northbound shoppers and tourists wait in line to enter Arizona.
The screens - just south of the DeConcini Port of Entry - flip through a variety of advertisements: a clinic to treat drug addiction, lawyers, restaurants and banks.
One of two obstetricians from Nogales, Ariz., who advertises maternity services on the billboards, said it's a way to promote the superior service, not U.S. citizenship rights that are granted to children born on U.S. soil.
Dr. José Durán, a gynecologist and obstetrician with 25 years of experience, said he's always had women coming from Mexico to have their babies but decided to announce his services on one of the screens because colleagues were doing it.
"People don't come for the citizenship," Durán said. "They come for the services and the technology that in some other places they don't have."
For decades, women from Mexico have traveled to doctors and hospitals in U.S. border states to give birth. In the 1960s, some of the first maquiladoras in Sonora offered medical insurance that covered the cost of maternity services in the United States.
"It's a tradition," Durán said.
But in recent years, more doctors and even some hospitals have started advertising their services in Mexico.
The practice is troubling to some.
Steven Camarota, research director at the Center for Immigration Studies, which favors strict enforcement of immigration laws, said authorities should crack down on these doctors who are putting greed ahead of the best interests of their own country.
Just publishing the names of the doctors would likely bring the practice to a halt, he said.
"It's part of the toleration of immigration abuses," Camarota said. "We don't enforce much; we tolerate a lot of fraud and abuse."
The United States recognizes the jus soli doctrine, which grants citizenship to those born on U.S. soil. And like the United States, Mexico honors the jus sanguinis doctrine, which grants citizenship to a child based on the citizenship of the parents regardless of where the birth occurs.
Officers at the ports of entry cannot deny a woman's entry into the United States, based solely on the fact that she's pregnant, officials said.
"As long as they have the proper documentation to enter the U.S., we'll let them in," said Joanne Ferreira, a spokeswoman with U.S. Customs and Border Protection. "They probably don't tell the officer, 'I'm coming to the U.S. to have my baby.' "
Durán said he does not keep a record on how many women from Sonora come to his office at 494 N. Carondelet Drive because of his ads on the screens. And he said those who do don't necessarily make their decision after seeing his ad.
He said both countries benefit from what each has to offer.
"People go to Mexico, receive less-expensive dental services and no one complains," Durán said. "We should be better neighbors."
Birth costs range from $1,300 to $2,100, depending on whether it's a vaginal or Caesarean birth. Durán noted that his patients pay in cash or have international health insurance.
Dr. Marco Saucedo - the other doctor promoting his services on the screens - did not return phone calls seeking comment.
The screens, which flash a different advertisement every 20-25 seconds, are relatively new in Nogales, Sonora.
Impacto Visual, the company that sells ads for the screens has no content restrictions, as long as it's not offensive, said Yesenia Luna, who oversees sales.
Currently Luna has about 40 customers. The screen ads cost about $332 per month.