Neighbours heard the baby whimpering but thought it was an injured cat and took no notice, the court was told.
The baby's body was later found in the back yard of the teenager's home in Willesden, north-west London. The 61 2 lb girl had died from head injuries and exposure, Ann Curno QC, for the prosecution, said.
The 16-year-old, who gave birth during the night on the floor of the bedroom she shared with her younger sister, who slept throughout, admitted infanticide in April this year.
Judge Heather Steel ordered the girl should not be identified and postponed sentence until next month.
Miss Curno said the girl came from Jamaica to join her mother last summer and within a month she was pregnant by her mother's boyfriend who allegedly raped her. The court was told that she now lived with an aunt.