A US woman has been in a vegetative state for over 10 years. Last week, she gave birth.

A woman said to have been in a vegetative state for at least a decade at a private health facility in the US is reported to have recently given birth, sparking a police investigation.

Reports first emerged on Thursday that a woman gave birth on December 29 at a Hacienda HealthCare facility in Phoenix where staff were unaware she was pregnant.

It is understood the woman, who has not been identified, was the victim of a near-drowning more than 10 years ago.

Reports said she was heard to be moaning and the baby’s head was starting to emerge when a nurse came in.

It is believed that the baby is in good health.

“None of the staff were aware that she was pregnant until she was pretty much giving birth,” a source was quoted as saying.

Following the initial reports, Hacienda HealthCare and state officials issued brief statements about the situation, expressing concern and describing reviews being conducted and steps being taken.

But they did not specifically confirm the reported pregnancy and birth.

Phoenix Police Department spokesman Sergeant Tommy Thompson said only that the “matter is under investigation”.

He declined to confirm whether the investigation involved a possible sex crime.

Hacienda said it was co-operating with police and reviewing its security protocols after becoming aware of a “deeply disturbing” incident and “an unprecedented matter”.

Hacienda’s website said it serves infants, children and young adults who are “medically fragile” or have developmental disabilities.

Governor Doug Ducey’s office said he was briefed on the “deeply troubling” reports as soon as the office learned of them and that state agencies “immediately began taking every measure to protect patient safety”.