Co-sleeping with babies could be fatal, reports the Herald Sun.

An unprecedented investigation reveals that since 2008, 33 infants have suddenly died in their sleep while co-sleeping with adults, the report said, raising alarm and prompting a coroner, John Olle, to hold an inquest on the pattern.

Victorian Coroner's Prevention Unit data shows 72 children aged between seven days and one year died suddenly as they slept. Of those, 33 had been sharing a bed, or other sleep surface, with an adult.

Nearly one in two sudden infant death syndrome cases in Victoria is related to co-sleeping. The investigation further found there had been seven co-sleeping infant deaths in 2008, jumping to 15 in 2010.

The inquest will carefully look into five child deaths, medical opinion from experts, and review of the adequacy of guidelines about SIDS (sudden infant deaths) and co-sleeping.

SIDS and Kids formal guidance says: "Sharing a sleep surface with a baby is a complex issue that encompasses many factors, and there is currently insufficient evidence to issue a blanket statement either for or against this practice."

"Some studies show increased risk (when co-sleeping with babies) and others show none, so there is conflicting evidence," says Murdoch Children's Research Institute associate professor Harriet Hitchcock, conceding parents received mixed messages when it comes to SIDS guidelines.

In the inquest, experts will discuss and debate on whether sudden infant deaths could actually be attributed to suffocation and even body heat from adults.