She has interim name suppression until the outcome of the trial.
Paramedic Caroline Davis told the court when she entered the house, she saw a distressed woman talking on the phone at the far end of a hallway and said something along the lines that her baby wasn't breathing.
The paramedic said she then saw a naked and weak-looking baby on the floor of the shower. A man crouched above her was trying to help her.
Davis said she picked up the baby, who was not breathing, was floppy, wet and cold, and put her on the kitchen table.
It was hard to do resuscitation on a child so young, she said, so they used defibrillator pads to check her heartbeat. There was none.
She started chest compression with her fingers given the age of the baby and did rhythm checks for about 30 minutes before pronouncing the child dead.
Davis said the bruising on the baby's forehead was about the size of a 50 cent coin and the one beside her mouth was equivalent to a five cent coin.
The bruises had turned green, she said, which led her to conclude they were not fresh.
During cross examination, defence lawyer Wayne McKean referred Davis to her police statement, which recorded her asking the male in the house what he did and how.
After a delay and following a deep breath, Davis said the man said something like "I smacked her two or three times on the chest".
Earlier, fire responder Corey Matchitt, of Fire and Emergency New Zealand (FENZ), who also attended the scene, said the male in the house said he struck the crying baby and made a slapping gesture towards his upper chest.
The trial before Justice Gerard van Bohemen is set down for two weeks.
