Australian researchers say that exposures to cigarette smoke induce abnormalities in babies' brains, thus putting them at increased risk of sudden infant death syndrome.
To reach the conclusion, researchers from University of Sydney analyzed the brain tissue of babies who had undergone an autopsy at Sydney's Glebe morgue.
After analyzing, they found exposure to any second-hand smoke could precipitate these brain cell changes, and not just exposure in utero by maternal smoking.
Rita Machaalani, a scientist at the university's Bosch Institute, and her colleague Karen Waters showed there was an increase in cell death in a region of the brain that plays a major role in the control of breathing and heart function in babies who died of SIDS, compared to those who died of other causes.
The post-mortems of 67 SIDS infants and 25 infants who died suddenly with another diagnosis between 1997 and 2002 were correlated with risk factors associated with SIDS, such as tummy sleeping, sharing a bed with adults and exposure to smoking, obtained during police interviews with the babies' parents and hospital records.
Of the 67 SIDS infants, 81 per cent had been exposed to cigarette smoke, compared to 58 per cent of non-SIDS infants, and 32 per cent were in bed with a parent when they died.
"No one in the world has access to such a large dataset of brain tissue or the ability to correlate the tissue with the autopsy results and a record of the risk factors and this is what makes our data really important," The Sydney Morning Herald quoted Machaalani, as saying.
The research has been published in the journals Brain and Acta Neuropathologica.
It found the increase in cell death (apoptosis) was higher not only in SIDS victims, but in all infants who had a history of tobacco smoke exposure, in utero and the postnatal period.