The death of a 15-day-old baby could have been caused by "unintentional suffocation" after his mother nodded off while breastfeeding in September last year.

She woke up about 1½ hours later to find the infant unresponsive and with dried vomit on his cheeks. Two hours later, the baby was pronounced dead in hospital.

In an inquiry last week into the death of Nor Eilshan Emran Muhammad Nor Aszroy, State Coroner Kamala Ponnampalam said there was no reason to suspect foul play.

While the cause of the death could not be confirmed, she added, it was likely to have been the result of "unintentional suffocation".

The mother's name was not revealed in court documents seen by The Straits Times, but it was indicated that Nor Eilshan was not her first child.

Senior nurse manager at KK Women's and Children's Hospital (KKH), Ms Teo Puay Ling, was quoted as saying in court documents that there are two preferred breastfeeding techniques.

One is the "football hold" position in which the baby is tucked under the mother's arm like a football.

The other is the "modified cradle hold", in which the baby is held in the crook of the arm opposite the breast he is feeding from.

State Coroner Kamala said: "(Ms Teo) stated that (KKH) does not encourage the 'side lying' method to avoid unintentional suffocation should the mother fall asleep during breastfeeding.

"Mothers may feel sleepy and doze off when the relaxing hormone oxytocin is released during breastfeeding... It is then important to have another person present to put the baby back in the cot if the mother falls asleep."

A routine screening at KKH after the baby was born on Aug 17 last year had revealed no abnormalities. Mother and son went to stay at his maternal grandparents' home in Sengkang after they were discharged on Aug 20 last year.

Twelve days later, at around 1.30am, the mother fed Nor Eilshan with her left breast by using the side lying method, and fell asleep.

When her husband woke up at around 3am to use the toilet, the noise woke her up.

She felt "something wet" as she moved her left hand to lift the baby, and asked her husband to turn on the lights. She found her son unresponsive, with vomit and bloodstains on his swaddling cloth.

An ambulance took the baby to Sengkang General Hospital, where he was pronounced dead at around 5am.