The "birth tourism" hotels hosted mainly Chinese women who paid between $15,000 (Â£9,756) to $50,000 for the services.
The raids focused on hotels suspected of engaging in visa fraud.
Court records said companies would coach women to falsify records and claims for their visa screening.
Birth tourism is not always illegal and many agencies openly advertise their services as "birthing centres".
The raids represent a rare federal crackdown against the widespread practice of foreign nationals giving birth in the US.
Undercover operation
It is estimated that 40,000 of 300,000 children born to foreign citizens in the US each year are the product of birth tourism, according to figures quoted in court documents filed to obtain search warrants for the schemes.
In one of the investigations into an Irvine "birthing centre", an undercover agent posed as a pregnant mother.
She was helped to provide false proof of income and a college diploma, told to enter through popular US destinations like Hawaii or Las Vegas and make reservations with hotels and tours.
A China-based "trainer" assigned to help put together the visa application asked for full-length frontal and side photo of the undercover agent's belly to see how visible her pregnancy was, according to agents.
Agents were also concerned that the schemes defrauded hospitals. Even though the women were paying birth tourism operators between $15,000 and $50,000 for their service, they paid local hospitals nothing or a reduced sum for uninsured, low-income patients, according to the affidavit.
No arrests were expected on Tuesday, according to the Los Angeles Times, but authorities said investigators would be seizing evidence and interviewing the mothers to build a criminal case against scheme operators.
Federal agents in California have raided more than a dozen hotels that cater to pregnant foreigners who want their children to be born US citizens.