Paola Vargas-Ortiz reportedly had to be talking down by police as she planed to hurl herself off the bridge.
The 37-year-old is said to have told officers her son was safe at home with her family before allegedly admitting she had hidden him inside a freezer at her house.
Officers convinced the mother to step down from the Seven Mile Bridge, Florida, US.
Ortiz confessed to have swallowed rat poison before she was taken to hospital, officers said.
Police then searched her Miami home where they found the boy.
According to detective Fernando Morales, the body was sealed in a freezer away from the main fridge-freezer.
Investigators are waiting on autopsy results as they look into the boy’s death.
Ortiz is undergoing psychiatric tests, officers said, Express reported.
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