Sonia Hermosillo, 31, has been placed on medical hold. She is expected to be in court for an arraignment hearing on Monday.
Prosecutors amended the criminal complaint from attempted murder to murder on Wednesday after her 7-month-old boy died.
Her husband says Hermosillo suffered from postpartum depression and couldn't accept her son's medical condition.
If convicted, she faces up to 25 years to life in prison.