This finding supports current recommendations to avoid head covering to reduce the risk of SIDS, lead author Dr. Edwin A. Mitchell, from the University of Auckland in New Zealand, and colleagues note in the medical Journal Pediatrics.
They point out that in UK guidelines, a "feet to foot" approach (placing the infant's feet at the foot of the cot) is recommended as a strategy to prevent the infant from sliding underneath the bedding. Despite this recommendation, it was unclear if head covering, which is seen in roughly 25 percent of SIDS cases, contributed to death or if it was associated with another event, according to the report.
To answer this question, the researchers analysed data from 393 SIDS cases in the New Zealand Cot Death Study (1987 to 1990) and from 333 cases in a German SIDS case-control study (1998 to 2001).
Overall, 15,6 percent of infants in the New Zealand study and 28,1 percent in the German study had their heads covered, the report indicates.
Infants whose heads were covered were often very sweaty, the researchers found, which suggests that the covering occurred before death. Older infants were more likely than younger ones to have their head covered, which likely reflects motor development.
In both studies, head covering correlated with the occurrence and severity of red spots on the thymus gland, which suggests low platelet counts. By contrast, head covering was not associated with the position the child was placed to sleep, or with the position the child was found in at death.
While the new findings support SIDS prevention strategies, research is "urgently" needed on how best to prevent head covering, the authors conclude.