Hannah Turtle, 22, from Shotton, Flintshire, suffocated seven-week-old James Hughes in June 2016.
She stopped his breathing on two other occasions before she killed him .
She also admitted five other child cruelty charges including administering poison to him, by putting her anti-depressant in James’s milk bottle on two occasions.
Turtle initially denied harming her son when questioned by police but was re-interviewed after she told social workers that she had killed him.
Turtle had said she wished she had not done it and said she needed help.
She also said she heard voices telling her she was a bad mother, and added that she had been abused as a child, suffered from depression and had mental health problems.
While there had no evidence of mental illness Turtle had been assessed as potentially having post-natal depression in the days before James’s death.
She must serve at least 14 years and nine months in prison.