PHOENIX -- A woman 8 months pregnant who was found unconscious on a Valley roadway Saturday morning has died, Phoenix police detectives said.

The victim is identified as Sylvia Russell, 35.

Officers responded to a check welfare call around 3 a.m. Saturday at 39th Avevue and Thomas Road, said Detective Cindy Scott of the Phoenix Police Department.

When they arrived, they found Russell unconscious in the roadway, Scott said.

She was transported to a local hospital where she was pronounced dead, Scott said.

Her family said she had just celebrated her 35th birthday last Wednesday.

"This is an ongoing investigation," Scott said in a police report.

At this point, investigators have not determined the cause of death.

The family said it hoped someone who knows something about her death will call police.