A THREE-MONTH-OLD boy who had been sleeping on a sofa was later found lying face down on the mattress in the living room by his father when he woke up several hours later, a coroner's court heard on Tuesday.

The father, Mr Noorizan Noordin, and his two daughters, aged four and two, had slept on the mattress on the floor in their Woodlands flat on Aug 31 last year.

When the 31-year-old service technician woke up at about 2.40am he noticed his elder daughter's leg on the back of the baby's head. The baby was found with his face down on a pillow, his body stiff.

Shortly later, when Madam Siti Raihan Mohamed Salleh, 23, a waitress, returned home from work, Mr Noorizan told her the baby was not breathing. She called an ambulance.

The infant was pronounced dead at National University Hospital at about 4am the same day.

The court heard that Madam Siti had placed the baby on the sofa to sleep at about 8pm before she left for work. It was also Mr Noorizan's practice to put the mattress on the floor in front of the sofa and television for him and daughters to rest and watch TV.

Consultant forensic pathologist Dr Teo Eng Swee, who did an autopsy on the infant, said in his report that death could not be ascertained, but he did not rule out suffocation or Sudden Infant Death Syndrome (SIDS).

SIDS refers to the sudden unexpected death of an infant in which autopsy fails to reveal an adequate cause of death.

Dr Teo stated that suffocation was possible even when no injuries or pressure marks were found on the baby.

Also, suffocation due to smothering, accidental or otherwise, could not be definitely excluded either as smothering in infants often did not leave any signs that could be seen at autopsy, he added.

In returning an open verdict, State Coroner Ronald Gwee said it could not be established how the baby came to be on the mattress.

'Parents, caregivers of infants and young children should take great care to ensure that the sleeping position of the infant or young child is safe, and there is no danger or infant or child falling from a height such as a sofa, or accidentally being smothered by a sibling or adult sleeping,' he said.

Mr Noorizan, who attended the inquiry into his son's death on Tuesday, said outside the courtroom that he had tried so hard to get a boy, and would try again, but 'not so soon'.

'I am very scared already,' he said.