When a 14-year-old student gave birth prematurely at 31 weeks in her home toilet, she called her 18-year-old boyfriend for help.

Turning up at her flat, the boyfriend, also a secondary school student, panicked over what to do next and suggested they place the baby outside his home so that his family could raise the child. He wanted to see his son grow up, without anyone knowing he is the father.

The couple placed the baby in an SG50 bag and walked over to the boyfriend's home. But his father called the police when he discovered the baby on his doorstep.

Yesterday, the 18-year-old was convicted of doing a rash act to endanger a human life by leaving his newborn baby unattended. He was also found guilty of four counts of underage sex with his girlfriend.

A Community Court heard that the young couple had first met at a function celebrating the birth of a baby to the girl's neighbour.

In January last year, after she turned 14, the two had unprotected sex on a staircase landing at the HDB block where she lived. A few days later, they had sex again at the same place. They then decided to focus on their studies and to meet less frequently.

Some time in May or June, she told her boyfriend she was pregnant. Both kept the news to themselves. On Aug 2, at about noon, the girl had stomach pains. While on the toilet seat, she felt extreme pain, and then heard a baby crying.

She looked into the toilet bowl and saw the baby. She picked up her newborn child, washed him in the sink, and called her boyfriend.

Before leaving their child outside his home, the boyfriend wrote a letter and placed it in the bag with the baby. It asked for "help to take care of this baby because I cannot afford to take care of him". "His name has been decided as (redacted)... if I have extra income, I will send money monthly," it also said.

At about 4pm, the boyfriend's mother found the half-zipped SG50 bag and took it inside her home. She unzipped the bag and heard some sounds. Thinking it might be a baby or a kitten, she placed the bag back outside and woke up her husband.

He called the police when he saw it was a baby, and paramedics later took the infant to hospital. At about 9pm, the young couple confessed to the boy's father. DNA analysis confirmed the baby is theirs.

The boyfriend will be sentenced next month, pending a probation suitability report. It is not known who is caring for the infant now.