Sleeping position and cot death – a scientific mistake that led to many thousands of extra infant deaths around the world (based on Webb, 1995)
This is an edited extract of from the text of my unpublished book about error and fraud in science; one of my error case studies. A shorter account and more limited account of this issue was made in an entry made on this blog some time ago.
During the 1970s and early 1980s there was a general belief amongst baby care “experts” that babies should be put down to sleep on their fronts rather than on their backs. The front sleeping position was believed to be safer than the back sleeping position traditionally used by most people in Western Europe. As a result of the almost unanimous advice from doctors, midwives, health visitors and baby care writers, the majority of parents adopted the front sleeping position. This promotion of front sleeping was based largely upon speculation rather than firm evidence of any benefit in normal healthy babies. During the 1970s and 1980s, as parents switched to the front sleeping position, cot death rates in many countries around the world rose sharply e.g. by around six to seven fold in the UK. During the mid-1980s increasingly persuasive evidence started to emerge that front sleeping was associated with a greatly increased risk (3-8 fold) of cot death. This evidence led to a change in advice to parents who were now advised to revert to using the traditional back sleeping position. In the UK a “back to sleep” campaign began in 1991 and was followed by an immediate halving of cot death rates in the UK in 1992. Front sleeping has returned to being an uncommon choice in the UK and cot death rates are now similar to the low rates seen at the start of the 1970s. Tens of thousands of extra cot deaths in the UK and probably hundreds of thousands around the world were almost certainly caused by this misguided promotion of front sleeping. Despite the devastating consequences of this mistake there has been relatively little public discussion of this error. Indeed the “back to sleep” campaign is often portrayed as a positive benefit of health promotion rather than the correction of an earlier costly error. Other errors made by officials or companies that have caused far fewer unnecessary deaths have quite rightly received extensive critical media coverage over a long period but many people are unaware of this error and its consequences.
Promotion of front sleeping – the Dutch experience
In the Netherlands a public campaign began in 1972 which advised parents not to lay their babies down to sleep on their back; this amounted to a de facto “front to sleep” campaign. It has been estimated that under 10% of Dutch infants were laid down to sleep on their fronts in 1965 and this figure was essentially unchanged in 1970. By 1980 more than half of Dutch babies were laid in this front sleeping position and this reached well over 60% of babies by the mid1980s. Between 1970 and 1980 the cot death rate in the Netherlands more than doubled and by the mid1980s it had trebled compared to that recorded in 1970. In 1987 a new campaign was mounted in the Netherlands which reversed the previous advice and advised against front sleeping and there was a 40% fall in Dutch cot death rates in 1988 compared to 1987 as the use of the prone sleeping position fell below 30% (see DoH, 1993).
The promotion of front sleeping – the UK experience
Historical evidence suggests that from the 15th century through to the middle 20th century babies in the UK were almost invariably put down to sleep on their backs. In the 1955 first British edition of Dr Spock’s famous Baby and child care book he favours back sleeping over front sleeping and does not mention side sleeping. In the 20th century the side sleeping position started to be used because of the largely assumed risk that babies sleeping on their backs might inhale regurgitated milk and choke on their own vomit (Hiley, 1992).
Before 1970 the use of the front sleeping position in the UK and many other industrialised countries was estimated at less than 5%. During the 1970s and 1980s the frequency of front sleeping increased until it became the majority position; one survey in the Avon district of England found 60% of infants were put down on their fronts in 1987 (DoH, 1993).
This belief in the superiority of the front sleeping position stemmed from some very limited reports from special care baby units that babies with respiratory problems might benefit from front sleeping and also the seemingly reasonable assumption that babies with severe gastro-oesophageal reflux (milk regurgitation) might be less likely to choke when sleeping on their fronts (see DoH, 1993). This flimsy evidence, based upon limited observations in special categories of high risk babies, led to the almost unanimous assumption amongst those advising new mothers that the safest sleeping position for all babies was on their front.
In a brief survey of baby care books published in the 1970s and early 1980s (see Webb, 1995) I found that they almost of all those that I could obtain recommended front sleeping; even the 1984 edition of the semi-official Pregnancy Book published by the then Health Education Council. Some quotes from these older baby care books are listed below.
“For the first two months or so, the safest way for babies to sleep is on their fronts, head to one side, or else curled up on one side. Then if they are sick there is no chance that they will choke. Kohner (1984) Pregnancy Book published by the Health Education Council: London.
“It is now felt safer for babies to sleep on their stomachs” Jolly (1981) Book of child care. George Allen and Unwin: London.
“I prefer them on their side, or on their stomachs” Luben (1986) quoting a midwife in Cot deaths: coping with sudden infant death syndrome. Thorson’s: Wellingborough.
“A young baby is best not left alone lying on his back. Because he cannot move very much he might choke if he were sick. Lie the baby on his front with his head to one side, or on his side. Reader’s Digest Association (1986) Reader’s Digest family medical adviser.
“Put your baby down on his or her tummy or side. Facing upwards, babies can choke, or be woken by their own waving arms and legs. Kohner (1986) The parent book National Extension College/BBC, Cambridge/London.
“The safest position is lying on the stomach with head to one side. Any regurgitated milk will dribble out of the mouth, so there is less risk of choking”. Harvey (1988) New parents Hamlyn, London.
I also found strong recommendation of front sleeping in Dutch and German medical journals:
From the German – Prone sleeping guarantees the normal psychological and physiological development of the baby – taken from a very powerful and influential avocation of front sleeping with a list of developmental and acute problems associated with back sleeping. Reisetbauer and Czermak (1972) Padiatrische Praxis (Paediatric Practice) vol 11, pages 5-14.
From the Dutch – It is our personal experience that babies in the prone position are calmer, more contented, and sleep better. Anon (1971) Ned. T Geneesk (Dutch Journal of Medicine) volume 117 (part48) page 1823.
In my admittedly limited and random survey of older books I could obtain from public libraries, I found only one published prior to 1986 that did not advocate front sleeping:
“The position of the child does not really matter”…..”There does not appear to be any real evidence that a baby is likely to choke if he is lying on his back and vomits. The dangers have probably been exaggerated.” Haslam (1984) Sleepless children” Judy Piatkus, London.
Not surprisingly front sleeping became much more common in many western countries throughout the 1970s and early 1980s. Incidence of cot death also rose during the 1970s and 1980s and peaked in the UK in the late 1980s at a rate of about 2 cot deaths per 1000 live births compared to the rate of around 0.3 per 1000 in 1971. By the mid1980s evidence started to emerge that babies who slept on their fronts were up to 8 times more likely to suffer cot death than those who were put down in the recommended face down position. This trickle of evidence and its reporting in the media led to a gradual reduction in use of the front sleeping position and a slow drift downwards in the number of UK cot deaths between the late 1980s and 1991. Compare the following quotation from the 1989 edition of Cot deaths: coping with sudden infant death syndrome by Luben with that of the 1986 edition listed above:
“Some recently published research, though, has suggested that sleeping on the tummy may have an association with cot death. …”The Foundation” (for the Study of Infant Deaths, FSID) “now normally advises that parents should adopt the traditional measure of lying babies on their sides”
Then in 1991, the UK government responded to this accumulating evidence and launched its “back to sleep” campaign aimed at persuading parents to use the traditional position of sleeping on their backs. This may seem like a rather slow response given the Dutch experience discussed earlier.
Note how the advice in the 1993 edition of the Pregnancy book had changed compared to the 1984 edition:
“Babies laid to sleep on their tummies are more at risk of cot death than babies laid down to sleep on their backs or sides…Only lay your baby down to sleep on his or her front if your doctor advises it”
In the year following the launch of the “back to sleep” campaign (1992) the number of cot deaths in the UK halved and it has continued to edge downwards ever since and is now similar to the very low rate seen in 1971. The figure shows the rates of cot death recorded in England and Wales at mainly 5 yearly intervals between 1971 and 2004. The rise in cot deaths between 1971 and its peak in the late 1980s is clearly shown. Rates started to drift slowly down prior to 1991 presumably as the growing suspicions of a link between front sleeping and increased risk gradually filtered through to health professionals and better informed parents. Then between 1991 and 1992 the rate dropped by 50% when the “back to sleep” campaign began and has continued to drift downwards and is now below 1971 levels. This campaign has been hailed as a triumph for health promotion that, according to The Foundation for the Study of Infant Deaths in 2006, had saved the lives of perhaps 20000 British babies. Indeed it has sometimes been used on health promotion courses as an illustration of the potential benefits of an effective health promotion campaign. The British Secretary of State for Health is quoted as saying in May 1993 when the 1992 fall in cot death rates was reported:
“The figures on cot deaths show that behaviour change can work, can save lives”.
What is not often fully acknowledged is that front sleeping only became common in the UK and many other western countries because of its promotion by health professionals and baby care writers. Tens of thousands of extra babies almost certainly died in the UK over the period 1971-1991 as a result of the misguided promotion of front sleeping. Worldwide, hundreds of thousands of extra babies probably died as a result of the promotion of the front sleeping position. The 20000 babies lives that according to The Foundation for the Study of Infant Deaths the back to sleep campaign “saved” are babies who would only have been at risk because of the earlier promotion of front sleeping by health care professionals and baby care writers. I wrote a fuller account of this example for an education journal (Webb, 1995) and brief update in a midwifery journal (Webb, 2006). I have also used it in my teaching to illustrate the potential dangers of promoting changes in behaviour before proper evidence-based evaluation of the risks and benefits has been undertaken.
Figure 1 Changes in the rate of cot death recorded in England and Wales over the period 1971-2004 – the red bar shows the rate in 1992 which was the year after “back to sleep” was launched.
I only wrote about this example “after the fact” and thus I was able to write with the benefit of hindsight. I did however have doubts about front sleeping many years earlier when I saw a newly born nephew being laid down on his front because my sister in law had been told that this was the safe position. It looked to me like a very unnatural position to use and so I was very receptive to early reports of the link between front sleeping and cot death. My own daughter, born in February 1989, was not laid on her front because of my awareness of this link despite front sleeping still being officially recommended.
Webb, GP 1995 Sleeping position and cot death: does health promotion always promote health? Journal of Biological Education 29(4), 279-285.
DoH (1993) Report of the Chief Medical Officer’s Expert Group on the sleeping position of infants and cot death. HMSO, London.
Hiley, C (1992) Babies’ sleeping position. British Medical Journal 305, 115.
Webb, GP (2006) Cot deaths: the benefits and dangers of health promotion. British Journal of Midwifery 14, 670.
Previous blog post on cot death here