The European Concerted Action on SIDS 'ECAS' Study
A case-control study incorporating data from 20 regions in Europe between 1992 and 1996. 745 SIDS cases and 2411 controls. Compilation of data collected from Sweden, Norway, Denmark, Britain (CESDI), Ireland, Germany, Netherlands, Austria, Hungary, Ukraine, Spain, Italy, Russia, Slovenia, France, Belgium and Poland.
In addition to the usual socioeconomic factors associated with SIDS risk, highly significant risk factors included:
- Position: prone sleeping (mOR 13·1, CI 8·51-20·2]) and turning from side to prone (mOR 45·4, CI 23·4-87·9). Approximately 48% of cases were attributable to sleeping in the side or prone position.
- Smoking [during pregnancy] and bed-sharing: Association between maternal smoking and risk associated with bed-sharing, especially for younger babies (at 2 weeks mOR 27·0, CI 13·3-54·9).
- Alcohol and bed-sharing: Mother's alcohol consumption was significant when baby bed-shared all night (OR increased by 1·66, 1·16-2·38 per drink).
- OR for non-smoking-in-pregnancy bed-sharers overall was very small and non-significant (1·56, 0·91-2·68), but became statistically significant in age-grouped analyses for babies aged < 8 weeks (at 2 weeks OR 2·4, 1·2-4·6).
Very large SIDS-risk analysis compiling data from studies conducted across Europe.
Not all variables recorded for all sites, different numbers of controls per case included from different sites.
Lends support to the importance of previously identified biological, socio-economic and environmental factors. Contributes to data relating to the interaction between smoking, alcohol and bed-sharing. Authors propose that bed-sharing is an independent risk factor, even for infants of non-smoking mothers, when aged < 8 weeks.
The Confidential Enquiry into Stillbirths and Deaths in Infancy (CESDI) Study
A case control study conducted in 5 regions across England between 1993-1996. 325 SIDS cases and 1300 controls.
Objective - to investigate risks of SIDS and factors associated with unsafe sleep environments.
- Increased risk of SIDS for bed-sharing babies (overall mOR = 9.78, CI 4.02 to 23.83).
- Risk associated with bed-sharing not significant for babies >14 weeks or for babies of non-smokers at any age.
- Risk became non-significant after adjustment for other factors comprising "recent maternal alcohol consumption ( > 2 units), use of duvets ( > 4 togs), parental tiredness (infant slept <4 hours for longest sleep in previous 24 hours), and overcrowded housing conditions ( > 2 people per room of the house)"
- Separate room (mOR = 10.49,CI 4.26 to 25.81) and sofa-sharing (mOR = 48.99, CI 5.04 to 475.60) also significantly associated with SIDS, the latter by far most risky environment.
Largest UK-based study to date.
The extreme importance of smoking among bed-sharing parents of infants who died (91.4%) made it impossible to precisely estimate risk for non-smokers (numbers of non-smokers very small).
Sofa-sharing and lone sleeping both high risk environments. Room-sharing associated with lower risk.
Risk of SIDS for bed-sharing with smoking was very high. No increased risk associated with bed-sharing for non-smokers or babies over 14 weeks of age. The authors suggest that the increased risk with bed-sharing for younger infants seems to be associated with alcohol and duvet use, overcrowding and parental tiredness.
A study of the sleep development of ~160 infants WHERE??
70% of infants began 'sleeping through the night' at 3 months of age.
The idea that infants should start sleeping through the night from 3 months of age originated from this study, and gradually became part of 'popular' or 'common' knowledge, and is still a belief held by many parents and health professionals today. There were, however, some big problems with this research and the way it was interpreted, which mean this belief is actually unfounded.
- Sleeping through the night in this study was classed as the infant not crying or fussing enough to wake the parents during a 5 hour period from midnight to 5am: this is not necessarily what modern parents mean when they expect their infant to sleep through the night!
- Researchers didn't take account of where infants were sleeping: if they were in a different room it is likely that parents didn't actually know whether they had woken or not during this 5 hour period, leading to more infants being classed as 'sleeping through' than was actually the case.
- Although 70% of infants were sleeping through by 3 months, this means that 30% had not slept through by 3 months.
- Being counted as having 'slept through' did not necessarily mean infants were regularly sleeping through. Moore & Ucko report that no matter what age sleeping though began, half the sample went back to night waking.
- The study was done at a time when formula-feeding was the most common feeding method. Formula-feeding has an important effect on the way infants sleep, so the findings of this study cannot tell us much about 'normal' (i.e. breastfed) sleep.
In summary, the research done by Moore and Ucko in the 1950s has had a disproportionate influence on how parents expect their infants to behave, and when they expect them to 'start sleeping through'.