Nathalie De Mey, 32, was convicted by an all-female jury in the southwestern French city of Carcassonne for the February 2, 2011, murder.
Murder of a minor is normally punishable by a life sentence, but De Mey's term was reduced because she was deemed to have had a temporary loss of judgement.
Yesterday when De Mey was asked why she did not choose a "more violent" method to kill the infant, she replied: "I didn't want to hurt him."
De Mey, who has two living daughters, said she had gone on several alcoholic binges during her pregnancy.
"When I realised I was pregnant, I tried to get help... but it was too late," she testified.
She recounted how she gave birth to the child over a toilet.
"When the baby came out, I caught him by the head so he wouldn't fall in the water, then I cut the cord with scissors."
Hours later, she said, she placed the baby, swaddled in a blanket, in the freezer.
Her lawyer said before the trial that De Mey had been afraid of admitting to her estranged companion that the third child was not his.
