Provisional figures suggest the number of sudden infant deaths last year could have been the highest since 1991, according to the Irish Sudden Infant Death Association.
Last year there were 69 suspected, but not yet confirmed, cases of sudden infant death, compared with 38 cases the previous year and 33 the year before.
The figures were described as a cause for concern by Prof Tom Matthews, chairman of ISIDA's scientific advisory committee. "These figures clearly tell us that sudden infant death syndrome is far from a problem solved, and we must intensify our research work to resolve this baffling phenomenon.
"Each month at least five children die suddenly and unexpectedly and often without explanation."
For the five consecutive years from 1992 to 1996, there was a greater-than-average proportion of parents who smoked, were unemployed or were on the medical card among families affected by sudden infant death.
Prof Matthews repeated three guidelines for parents to reduce the risk of cot death: do not smoke during pregnancy and around children; avoid making babies too warm during sleep; and place babies on their backs to sleep.