The stabbing of three babies in Queens last September opened a window into an unregulated and underground phenomenon – "maternity hotels" that care for their newborns and their mothers, many of them from China.

Some of the people who use "maternity hotels" are Asian women already living in New York, but many travel to the U.S. just to have a baby so the child automatically can become an American citizen, a practice known as birth tourism.

NY1's Clodagh McGowan found at least 36 of them in Queens alone, facilities that appear to operate with little oversight, benefitting from loopholes in state and city regulations governing child- and health-care facilities.

In a three-part series, McGowan takes a closer look at these maternity hotels and how they are able to escape oversight. She also looks at the phenomenon of birth tourism, and examines whether taxpayers might be picking up some of the medical bills.