Tulare County Sheriff's Deputies arrested Nikki Ray of Terra Bella on Saturday.
They say she brought her baby to a local hospital with a fever and in a dazed state.
Doctors discovered the one year old had excessive amounts of a psychoactive marijuana chemical in her system.
Investigators say Ray is a medicinal marijuana user and often smokes in the presence of her baby and her three-year-old child.
She's now booked in jail on child endangerment charges. Both children are now in protective custody.