A study published on bmj.com today reports that more than half of unexplained sudden infant deaths occur while the infant is sharing a bed or a sofa with a parent (co-sleeping). In addition, it may be associated to parents drinking alcohol or taking drugs.

Since the early 1990s, the rate of cot death in the UK has fallen significantly. However, the researchers say that explicit advice to avoid dangerous co-sleeping arrangements is needed to help reduce these deaths even further.

The term sudden infant death syndrome (SIDS) was introduced in 1969. It is a recognized category of natural death that carried no implication of blame for the parents.

Nowadays, we know much more about risk factors. Parents are now advised to reduce the risk of death by placing infants to sleep on their back, placing babies in the “feet to foot” position at the bottom of the cot, and keeping infants in a smoke-free environment.

But it is unclear which risk messages have been taken on board in different social or cultural groups. Moreover, little is known about the coming out of new or previously unrecognized risk factors.

In order to find out more, a team of researchers at the Universities of Bristol and Warwick studied all unexpected infant deaths from birth to two years in the southwest region of England from January 2003 to December 2006.

They examined the potential link between SIDS and socioeconomic deficiency. They compared these deaths with a control group at ‘high risk’ for SIDS which were young, socially deprived mothers who smoked, as well as a randomly selected control group.

Shortly after the death, parents were interviewed. Information on alcohol and drug use was collected. Trained professionals conducted a detailed investigation of the scene and circumstances of death.

They analyzed a total of 80 SIDS deaths. More than half (54 percent) occurred during co-sleeping compared to a 20 percent co-sleeping rate among both control groups.

The authors say it appears that much of this risk may be explained by the combination of parental alcohol or drug use prior to co-sleeping with 31 percent compared with 3 percent random controls. The high proportion of co-sleeping deaths on a sofa with 17 percent compared with 1 percent random controls.

A fifth of SIDS infants were found sleeping with a pillow when they died. A quarter was swaddled. This suggests the emergence of potentially new risk factors.

The risk factors were similar in the different groups of SIDS cases. This indicates that these risk factors for SIDS apply to all sections of the community and are not just a consequence of social deprivation.

The authors remark: “Some of the risk reduction messages seem to be getting across and may have contributed to the continued fall in the SIDS rate.” However, the majority of the co-sleeping SIDS deaths occurred in a hazardous sleeping environment. They recommend that the safest place for an infant to sleep is in a cot beside the parental bed in the first six months of life.

It is essential that parents be advised to never put themselves in a situation where they might fall asleep with a young infant on a sofa. They also need to be reminded that they should never co-sleep with an infant in any environment if they have been drinking or taking drugs.

In an associated editorial, Edwin Mitchell, Professor of Child Health Research at the University of Auckland comments: “We have learnt that SIDS is largely preventable. It is important to monitor parents’ knowledge and infant care practices to inform health education and promotion.”

He says in closing: “Implementing what we already know has the potential to eliminate SIDS, the challenge now is how to change behavior.”

Hazardous co-sleeping environments and risk factors amenable to change: case-control study of SIDS in south west England”
Peter S Blair, senior research fellow, Peter Sidebotham, associate professor in child health, Carol Evason-Coombe, research health visitor, Margaret Edmonds, research health visitor, Ellen M A Heckstall-Smith, research assistant, Peter Fleming, professor of infant health and developmental physiology
BMJ 2009; 339:b3666

“Risk factors for SIDS”
Edwin A Mitchell, professor of child health research
BMJ 2009; 339:b3466

Written by Stephanie Brunner (B.A.)