Meredith Borowiec gave birth in 2008 and 2009, but the two babies' bodies have never been found.
A third infant born in 2010 survived when the baby's father, not knowing it was his child, helped pull the newborn out of a neighbourhood trash bin after a passerby heard cries.
A trial judge ruled the mother's bizarre actions showed her mind was disturbed at the time of the births and found her guilty of infanticide instead of second-degree murder.
The Crown appealed the decision and asked for a new trial.
In a two-to-one ruling, the Court of Appeal said the trial judge considered relevant cases and expert evidence in his decision.
"The expert evidence before him conflicted in a significant way, and he preferred one expert’s conclusion over that of the other," said the decision.
"He found that the respondent was operating in a sort of individualized pocket of unreality that persisted in the period shortly following the births. The Crown has not persuaded us that there was an error of law in the trial judge’s conclusion in this regard."
Borowiec was sentenced to 3 1/2 years in prison.
In 2012, while in police custody, she gave birth to a fourth baby and the child was taken from her.
She later had an IUD inserted to prevent any pregnancies while on probation. She also agreed to a 10-year peace bond.
In interviews with police, Borowiec admitted that she heard her babies cry before she put them in trash bags and dropped them into garbage bins. She denied doing anything to hurt them beforehand.
She said she kept her pregnancies secret from co-workers by telling them she had cysts on her uterus. She said her boyfriend was unaware that she was pregnant either before or after the births.
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