Police found the dead infant and her mother Ae in bed at 5am yesterday at a townhouse on the Khlong Luang housing estate, said Sub-Lieutenant Amarin Wanthongpitak.

The infant's grandmother Noi, 41, told police that she woke up and was about to leave for work at a Bangkok hotel at 4.50am when she saw the baby lying still, facedown on a pillow, while Ae was sleeping on the other side of the bed. She called police.

Noi said she believed Ae was unaware of the danger of suffocating her child by putting her to sleep in such a position.

She said Ae became pregnant after she was raped by a conscript who broke into their home nearly a year ago. The man was jailed for raping a girl aged under 14, she said.

Since investigators found the family loved the infant, her death was likely an accident, Amarin said, adding that an autopsy will be performed to determine the cause of death.