Cot deaths or Sudden infant death syndrome (SIDS) is a rare cause of sudden unexplained death in infants.
Although no exact causes are known, there are known risk factors that may increase the likelihood of crib deaths. (1-5)
The risk of crib deaths include:
- sleeping on the stomach
- sleeping on a soft surface
- maternal or parental smoking
- overheating
- lack of pregnancy care
- young maternal age
- premature or low birth weight baby
- male babies
Higher rates of crib deaths are reported in black and American Indian/Alaska Native children. This is twice to thrice the national average. (2)
Frequency of cot deaths at different ages
The risk of SIDS in the first month of life is low.
The likelihood rises between 2 and 4 months after birth. Beyond one year the risk declines.
Frequency of cot deaths in US
In 1992, the SIDS rate for the United States was 1.20 deaths per 1000 live births.
In 2001, the SIDS rate was reported at 0.56 deaths per 1000 live births. This suggested a 53% decrease over 10 years. In 2002 the rate remained constant at 0.57. (2)
Reasons for decrease in cot death incidence
It is suggested that the public awareness and reduction in sleeping on stomach could be the reason for the decrease in the SIDS incidence.
In a national survey it was found that sleeping on stomach reduced from 70% in 1992 to 11.3% in 2002 and increased slightly to 13.0% in 2004.
The rate of SIDS among black infants was 2.5 times that of white infants in 2001. This correlated with the stomach-sleeping figures.
Among white infants stomach sleeping was seen in 11%, compared with 21% among black infants.
Earlier SIDS was more commonly seen in the winter months. This seasonal trend is also changing. (1-5)
Frequency of cot death worldwide
There were approximately 4,600 sudden unexplained deaths in infants a year as estimated in 2006.
In that year there were 2,323 SIDS deaths.
When analysed over 15 different countries it was noted that SIDS deaths have declined from the 1990’s to 2008.
These decreases range from 40% in Argentina to 86% in France.
In 1990, the highest SIDS rates were seen in Ireland, New Zealand, and Scotland at over 2 per 1000 live births.
At present the highest rates are seen in New Zealand and the United States at over 0.5 per 1000 live births.
The lowest rates of cot deaths are seen in Japan and the Netherlands (less than 0.2 per 1000 live births). (2, 3)
The trends reveal that the largest decreases in the rates of SIDS were between 1990 and 2000 mainly due to public awareness.
Rates of SIDS differ considerably across countries worldwide, ranging from 0.10/1000 live births to 0.80/1000 in 2005. This difference could be due to some basic disparities.
These include age of inclusion and definition of SIDS used in different countries.
For example, in Canada, England and Wales, Germany, and Scotland SIDS is defined as deaths occurring from one week to one year of life.
Argentina, Australia, Austria, France, Ireland, Japan, Sweden, and the U.S. include deaths from birth to one year while the Netherlands and New Zealand include deaths over a year as well.
In addition, risk factors are different in different countries. For example, the Maori in New Zealand and American Indians have the highest smoking rates and consequently have a high rate of SIDS. (2, 3)
Further Reading