Abstract □ 146

In the last few years co-sleeping has become increasingly disputed as a risk factor for sudden infant death syndrome (SIDS). The prone sleeping position on the other hand is a verified risk factor. Previous studies have shown an increased risk of SIDS associated with co-sleeping; some in correlation with mothers who smoke. The objective of this study was to analyse the changes in frequency of co-sleeping and SIDS during the time of increasing SIDS rate: 1984-1989, the period of rapid decline: 1990-92, and during the time of stable low rates: 1993-98. We looked at three-year intervals with regards to both co-sleeping and prone sleeping-position at the time of death.

Material and method: Data were obtained from the autopsy reports of all SIDS cases investigated at our institute between January 1984 and June 1998. Co-sleeping and sleeping-position at the time of death were registered. For those found to be co-sleeping, sleeping-position, whether the head was covered, breastfeeding, signs of infection, and parental smoking were registered.

Results: For the whole period 30 SIDS out of 215 from our region were found to be co-sleeping at the time of death. The proportion of co-sleeping in the SIDS population has increased significantly in the timeperiod studied (p<0.001)(Fig. 1). Most of the co-sleeping infants were breastfeed throughout the period and no difference was found for signs of infection. In the period 1984-89, 83% of the co-sleepers died in the prone position, whereas this was only true for 8% in the period 1990-98 (42% side, 29% supine). Information about parental smoking and heads having been covered by bed clothing were too scarce to be conclusive with regard to co-sleeping.

Fig. 1
figure 1

Percentage of co-sleepers ▪ and prone sleepers □ at the time of death during the period studied. Co-sleeping showed a significant increase (p<0.001), whereas prone sleeping-position showed a decline (p<0.001).

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Discussion: Several explanations for an increased risk of SIDS while co-sleeping have been postulated, such as accidental asphyxia, rebreathing of CO2 and overheating. It has been noted that in some cultures, where the SIDS rate is low, co-sleeping is a frequent mode of sleep for infants. Co-sleeping has furthermore been postulated as favourable since it promotes breastfeeding, supine sleeping and a lighter sleeping pattern (increase of arousal episodes).

Conclusion: The proportion of SIDS deaths occurring while co-sleeping has increased in eastern Norway during the period studied. The increase is especially evident during the last three years. In the same period the proportion of SIDS deaths occurring in the prone sleeping-position has declined.