FBI agents raided an Irvine apartment complex that was allegedly housing pregnant women as part of a "birth tourism" scheme (Screengrab via Fox News)

In a major sting early this morning, FBI agents raided 20 SoCal "maternity hotels" allegedly involved in a scheme that arranges for wealthy pregnant Chinese nationals to give birth to their children in America so the children can garner U.S. citizenship.

At different locations throughout Los Angeles, Orange and San Bernardino counties, Feds raided apartment complexes, aka "birthing centers," they believed were housing the pregnant women, as well as the homes of the masterminds behind the "birth tourism" scheme, reported the L.A. Times. Officials said there were three businesses they targeted.

The feds didn't arrest the women, but are treating them as material witnesses and interviewing them, according to NBC News. While birth tourism isn't illegal, the operators of the alleged schemes are in hot water and could face criminal charges. They're being accused of taking part in visa fraud and conspiracy by coaching women on how to obtain tourist visas, falsifying records and giving them pointers on how to talk to immigration officers at LAX, according to search warrant affidavits unsealed today.

Birth tourism operators charge foreign nationals tens of thousands of dollars to help them give birth in the U.S., according to the affidavits. Pregnant women reportedly paid $40,000 to $80,000 to stay at one of the birthing centers, a fancy, resort-like apartment complex in Irvine called the Carlyle, which comes along with amenities like a pool and cabanas. The women are pampered at these fancy digs with handlers acting as their chauffeurs, taking them around to restaurants and stores.

When they go into labor, they're sent to local hospitals, where they pay discounted rates: instead of $25,000, some of these women are only forking over $4,000 to nothing through claiming that they're uninsured, low-income patients, the affidavits said. Hospitals are apparently losing lots of money over these births.

These operations allegedly advertise the benefits that would come out of having a child with U.S. citizenship, which include free education, better air quality and a way for parents to eventually immigrate to America themselves.

One pregnant woman questioned who only went by her last name Wu, told the L.A. Times she wanted a better life for her future daughter. "If things were good in China, why would we need to come here?" she asked.

As for how widespread of a practice this is, a study mentioned in the affidavit found that 40,000 children a year were born to women on travel visas.