16-year-old Joshua Bacon allegedly shook his daughter Caitlyn Smith so violently that led to brain injury after he lost his patience while trying to feed her.
Bacon and his wife, Danielle Smith, 16, had taken their daughter to hospital in Jan 2009, where she was admitted with a minor urinary infection.
After spending the first night in the hospital, Smith left Caitlyn under the care of Bacon for two days.
Caitlyn was found dead on the day she was to be discharged. Bacon informed a nurse that baby had vomited and gone limp.
"I tried to feed her, but she didn't take it, so the nurse told me to try again soon. The second time, she didn't take it again, so I winded her and she was sick on me. I tried feeding her again, but half way through she started coughing and being sick again.
"So I put her down beside me and started watching TV, but the next time I looked at her she was pale and floppy. I don't regret anything because I didn't do anything wrong," Bacon told the Preston Crown Court.
Caityln injuries have been described as those incurred in a car crash or long fall on to a hard surface.