A man pushed his girlfriend's one-year-old son off a bed in anger with so much force that the baby landed on the ground 2m away - suffering a broken skull and bleeding in the brain, a district court heard yesterday.

Prosecutors said the child survived the ordeal on March 25 last year "rather miraculously" and is now in foster care. He is still undergoing rehabilitative therapy.

Yesterday, his tormentor Franklie Tan Guang Wei pleaded guilty to one charge of causing grievous hurt and three of ill-treating a child.

Tan, who turns 26 tomorrow, admitted to another count of child abuse, which will be considered in sentencing on Sept 19.

The prosecution is seeking seven years' jail with six strokes. It noted that Tan had no qualms in continuing his abuse of the baby, which began in November 2014, despite knowing that the Child Protective Service (CPS) was investigating him.

The child and his 25-year-old mother cannot be named to protect the boy's identity. He was born in mid-2013 after his father lost contact with his mother. In August 2014, she began seeing Tan. The next month, the infant's behaviour changed. "(He) appeared to be fearful of males and started having nightmares in his sleep," Assistant Public Prosecutor (APP) Dillon Kok said.

Two nannies who looked after him also found bruises on his body. "When (the mother) was questioned, she denied that (he) had been abused and claimed that there were 'spirits' in the flat."

On Nov 8, the baby's cries woke the couple. Tan slapped him once, leaving finger marks on his face and bruising near his ear. Three days later, a nanny took photos of the bruises and swelling. When confronted, the mother said he fell off the bed. The nanny made a police report on Nov 19 and the CPS was informed.

The baby was then put in the nannies' care and the couple were allowed only weekly supervised access. But in January last year, they were suspended from all contact after the baby was found with scratches on his thighs after a visit.

They were granted supervised access again the next month. But on March 8 last year, Tan's grandfather left the infant at Tan's flat. That night, frustrated with his cries, Tan threw the baby at his mother, who was about 2m away. The infant fell against her body.

Later, Tan and the mother were allowed to spend the nights with him. But on March 25, angered by the baby's cries, Tan hit his buttocks twice, causing a bruise. After the mother went to work, leaving the baby alone with Tan, the boy vomited on the bed. Angry, Tan forcefully pushed him off it with his right arm.

The child landed face-up about 2m away and vomited again. Tan took him to the toilet to shower, but did not check the water temperature first, scalding his upper back.

Later, Tan noticed the baby to be in a daze and semi-conscious. He was also vomiting repeatedly. Tan told the mother, who went home to find the infant weak and very pale. They took him to hospital, where he underwent emergency surgery.

The mother has been charged with two counts of permitting Tan to ill-treat the baby. Her trial is scheduled to begin on Sept 26.

It is not known if Tan and the mother are still together.