A SEVEN-month-old baby boy thrown off a multi-story parking garage in Orange, California, was clinging to life late yesterday (local time), while his mother was held without bail on suspicion of attempted murder.

Sonia Hermosillo, 31, was arrested early yesterday, with police alleging that she intentionally threw the child off the parking structure late Monday.

The infant was seen falling from the second or third level of the garage, which is attached to the nearby Children's Hospital of Orange County, at around 6:20pm local time, authorities said.

The boy was taken to the UC Irvine Medical Center in Orange, where he remained in a critical condition late yesterday, his father Noe Medina told The Orange County Register.

Mr Medina said his wife suffered from postpartum depression, also known as postnatal depression, and was hospitalized in June after she said she did not want her son anymore.

Their son, who bears his father's name Noe, reportedly had been diagnosed with congenital muscular torticollis - a condition that twists the neck to one side - and usually also wore a helmet to help correct his plagiocephaly, a condition known as flat-head syndrome.

"She didn't look at our son as normal," Mr Medina said, adding that his son was still in a critical condition with head injuries. "She didn't accept him. She didn't accept that he was like this."

An Orange County Sheriff's Department official told The Register that Hermosillo was placed on suicide watch after being held without bail on suspicion of attempted murder. She was also booked on an immigration hold.