The number of cot deaths is still "high" at weekends, despite the success of the Back to Sleep campaign, researchers have warned.
Research by researchers at Aberdeen University published in the Archives of Disease in Childhood, looked at the number and timing of cot deaths both before and after the campaign in the early 1990s, which urged parents to put babies to sleep on their backs.
An analysis of almost 13,000 deaths attributable to sudden infant death syndrome (Sids), often known as cot death, showed a dramatic reduction in the number of deaths from 1,718 in 1986 to just 395 in 1998 - a fall of about 75%.
But deaths from Sids peaked on Saturdays and Sundays, both before and after the campaign, the figures show, accounting for just under a third of the total number of deaths. The weekend peak was much more obvious among babies aged four months or younger.
The reasons for the weekend peak in cot deaths remain unclear, say the researchers. Parents may be less attentive to the needs of their infants over the weekend, it has been suggested. Reduced access to health services at weekends has also been suggested as a factor.
The Foundation for the Study of Infant Deaths (FSID) said it had "long been known" that cot deaths were more likely to occur at weekends than weekdays.
The charity said: "There is speculation as to why that may be, but no evidence-based answers. Until more is known about why these tragedies occur - through improved investigation of each death and through more basic research into causation - it is not possible to know for certain why babies are more likely to die at weekends."
It added: "It is important to note that the increased incidence of sudden unexpected infant deaths at weekends is very small - less than 4% greater than on weekdays - so parents should not be worried unduly by this."
But the charity warned that the system for investigating cot deaths was "inadequate - erratic and uncoordinated, and lacking in standardisation to ensure all data is collected and examined". Valuable information was being lost, and bereaved parents were unable to find out why their babies died, it said.
Only a third of the country is covered by a voluntary multi-agency protocol for medical and judicial professionals on investigating cot deaths and implementation in these areas is patchy. In most of the country, professionals have refused to accept the protocol, which FSID believes should now be compulsory.
A working group set up by the Royal College of Pathologists and the Royal College of Paediatrics and Child Health, chaired by Baroness Helena Kennedy, is due to report shortly and is expected to recommend mandatory measures.
