The parents of dying baby Kaylee say the transplant of her heart to another baby didn't go ahead as planned, because the two-month-old didn't fall asleep after she was taken off life-support.

The Hospital for Sick Children told parents Jason Wallace and Crystal Vitelli on Monday that their newborn's heart was strong enough to be transplanted to another child.

However, the transplant had to be performed quickly to prevent the heart from becoming damaged if it did not receive oxygen while the donor baby dies.

Kaylee's father Jason Wallace says his daughter did not fall asleep after she was taken off life-support as physicians had hoped. He says her heart would have been removed if she had died within two hours of being taken off the life-support.

Kaylee was taken off life-support at 5:30 p.m. on Tuesday. She has since been put back on life-support on Tuesday evening.

Kaylee has a serious brain condition that has worsened to the point where she was unable to breathe without a machine. Kaylee's parents know their daughter would die and want her heart to go to another baby.

Chief surgeon Dr. Jim Wright had said that both infants would be brought to a prepared operating room and if a legal death occurred where the donor baby's heart stopped beating for five minutes, surgeons would proceed with the transplant.

"If however, the baby does not die, then the donation of the heart will not occur," he said.

After Kaylee was put back on life support, Dr Wright said she is no longer a donar candidate, however if her situation changes, the hospital will reconsider the procedure.

The donor family has faced opposition from some doctors who said Kaylee's heart wouldn't be usable for transplant because it would take her too long to die after being taken off life-support.

The parents have taken photos of Kaylee, moulds of her hands and feet, and they say they are mentally prepared for what comes next.

Mr. Wallace says he wants the hospital to try to transplant Kaylee's heart again.

Provincial Health Minister David Caplan says he will not interfere in the case.

With files from The Canadian Press