Police said the woman, Grisel Ramirez, attempted to take the baby girl about 10 a.m. from the mother's Garden Grove Hospital Medical Center room.
Garden Grove Police Lt. Jeff Nightengale said hospital workers were alerted that the child might be in danger and of her location by an electronic monitor she was wearing. Workers near the exit confronted Ramirez, who was carrying the baby in a tote bag, and detained her until police arrived.
The baby was unharmed and reunited with her mother.
Police said there was no relation between the mother and Ramirez and that there were no additional suspects.
Nightengale said the suspect had made her way to the fifth floor, the maternity recovery ward, and slipped into the mother's room. The suspect suggested the mother bathe herself. When she did, the suspect allegedly took the opportunity to take the baby.
Nightengale said Ramirez was not cooperating with the investigation. He said she allegedly gave several different names, but investigators said they knew who they were dealing with. They said they think Ramirez is an undocumented immigrant who lives in Garden Grove. At this point, there is no known history of mental illness, they said.
Ramirez may have attempted similar kidnappings at other hospitals, Nightengale said.