The baby survived the incident.
She had originally been charged with attempted murder.- VIDEO | Calgarian found guilty of infanticide
"I have accepted what has happened and feel horrible about it. I will have to live with this," said Borowiec in court.
The guilty plea came during a sentencing hearing Wednesday involving two cases of infanticide. The 32-year-old had already been found guilty of the deaths of two other babies — one in 2008 and another in 2009 — who were also put into a dumpster.
"There are two babies that are dead who will never have the opportunity to partake in any of life's pleasures," said Crown prosecutor Jayme Williams.
"They lived a brief existence wrapped in a garbage bag, thrown in a dumpster. Then there is a third who lived because of good fortune."
Borowiec was originally charged with two counts of second-degree murder for the deaths. The trial judge ruled Borowiec was suffering from a mental disturbance at the time of the crimes and found her guilty of the lesser crime of infanticide.
Neither body was found.
Father discovered his own infant in dumpster
Borowiec said in all three cases, she hid the pregnancy from her longtime partner Ian Turnbull.
Turnbull was the one who found the third baby alive in the dumpster. He had come home from work during the day when he heard crying coming from the garbage bin near their home and discovered the infant.
He has told later by police the baby was his son.
Borowiec said Wednesday she hopes the child lives a "happy and fulfilling life."
The woman's defence team submitted letters of support for Borowiec from a psychologist, her father and a support worker at the Elizabeth Fry Society, a non-profit organization that aides women involved in criminal matters.
Defence lawyer Andrea Serink argued that Borowiec should not spend any more time behind bars. She has already served the equivalent of three years.
"She was the mother of the infants, she'll have to live with this for the rest of her life," she said.
Serink said Borowiec has expressed remorse and has a high potential to rehabilitate.
Borowiec had no previous criminal record.
A new sentencing hearing has been scheduled for Jan. 29.