BBC Sounds Music Radio Podcasts Hello and thanks for downloading the More or Less podcast with a programme that looks at the numbers in the news, in life and as advice in 1950s parenting guides. I'm Charlotte MacDonald. Sometimes it's obvious to everyone when an idea is harmful or a piece of advice is damaging. But not always. Occasionally bad ideas and terrible advice end up being accepted in society and supported by people in authority. In such circumstances, one of the most powerful tools for changing people's minds is evidence. Actual facts that show beyond doubt that the bad idea is indeed a bad idea. That's the subject of a new book by Helen Pearson, titled Beyond Belief – How Evidence Shows What Really Works. An editor at the scientific journal Nature and Her Day Job, the book chronicles those determined individuals who shake up the status quo by gathering just the right kind of evidence. One story in that book stood out to us here on More or Less, a kind of cautionary tale about what happens when you don't have the evidence you need to challenge a dangerous way of doing things. It's the story of one piece of advice from childcare expert Dr Spock. The story starts really with probably the best-selling parenting book of all time, which is Baby and Childcare by the American pediatrician Benjamin Spock. First published in 1946 and Spock's book quickly became this enormous bestseller, so the favourite childcare manual for new parents sold probably more than 50 million copies in over 40 languages in the end. In the first edition of Baby and Childcare, Spock told parents to put their babies to sleep on their backs. But in the 1958 edition, he made this small change where he started recommending that babies be put to sleep on their fronts instead. And he said that infants lying on their backs were more likely to choke on their own vomit and maybe end up with flattened heads if they slept that way. And his recommendation it wasn't just him, it was mirrored by many other sources and parents enthusiastically followed this advice. And the proportion of babies that slept on their fronts rose steeply in the US and some other Western countries during the 60s and 70s. But there wasn't really much evidence to support this advice, so it was basically what senior pediatricians like Spock thought to be correct. As it happens, Helen's mum also had a copy of the book. I have actually got my mum's copy of Spock's Baby and Childcare from 1958 sitting on my desk because during researching my book, I wanted to make sure that this was true. So yes, my mum followed this advice. She laid me down to sleep on my front. And if I turn to page 173, I think it is, hold on. I think it is preferable to a customer baby to sleeping on his stomach from the start if he is willing. I'm afraid this story is not a happy one. Because at the same time as more babies were being put to sleep on their fronts, another deeply troubling trend was emerging. A growing number of babies in some Western countries were dying suddenly in their cribs from what we now call sudden infant death syndrome or SIDS. The phenomena became known as Cot Death or Crib Death. It was eventually called an epidemic. And the cause of these rising deaths was a matter of fierce debate amongst doctors. No one really understood what was happening. There were lots of theories around it but no clear answers. And really what was missing in all of this was evidence from rigorous research. To gather the evidence you need, what you want or what Helen refers to as case control studies, where you compare the circumstances of babies who have died with a control group of babies. Differences between these groups might help you understand what's going wrong. In 1965, researchers in the UK published the first well-conducted case control study comparing over 100 children who had died with a control group. And they did notice and noted in their paper rather ominously that cases were found face downwards rather more frequently than the controls. But the data was a bit difficult to really pinpoint any particular cause. And then there was a second case control study published in 1970. And again it hinted that sleeping position was linked to increased risk. But the association wasn't deemed to be statistically significant. The problem with SIDS is that it doesn't appear to be a simple health problem with a simple cause. There were a lot of factors that were potentially associated with the baby's deaths. And in all that noise, the signal for front sleeping wasn't clear enough to come through. It actually took until 1986 for the link between sleeping position and SIDS to become clear. So by the late 1980s, much larger studies were coming out which showed that the death rate was higher in children who slept on their fronts. And eventually the weight of evidence was just impossible to ignore. Spock's advice about front sleeping had been dangerously incorrect. And here's the thing with evidence. Once you've got enough to act on, you get to see what happens when you, well, act on it. In 1991, the UK launched a back to sleep campaign, encouraging parents to put babies to sleep on their backs. Other countries did the same. And as back sleeping became the norm for parents, the incidence of SIDS dropped pretty much like a stone. And this really provided the strongest evidence of all that front sleeping increases the risk of sudden infant death, even though it's still not fully understood why. Front sleeping is not the only risk factor that makes deaths more likely. And other factors also changed over this time as they became clearer. But there is no doubt that the advice in the 1958 edition of baby and childcare was dangerous. This advocacy of front sleeping by Spock and other pediatricians is now understood to have been one of the most lethal pieces of unsubstantiated advice in the history of child health. And one thing that makes it more tragic is that this link with infant death might have been detected earlier. The one point of light in this story is that at the same time as this all was happening, scientists were developing new ways of amalgamating and analyzing scientific research in order to detect the signal from the noise. The systematic review and the meta-analysis were coming to the fore. What makes this story really interesting is that scientists actually went back and did that type of analysis. In 2005, they combined the data from the historical studies looking at SIDS and put them together with a meta-analysis. And what they discovered was very shocking to them because there had actually been sufficient evidence that front sleeping significantly increased risk as early as 1970 when just those very first two studies were pulled. And at this point, the data actually showed that front sleepers were three times as likely to die as those who slept on their backs. If that had been noticed, then scientists, doctors might have been able to take action. But instead, parents were commonly advised to put their babies to sleep on their fronts for many more years. And very sadly, this UK research team that did the meta-analysis calculated that at least 50,000 deaths of children in the USA, Europe and Australasia could have been prevented if evidence from research on SIDS had been synthesized and acted on in 1970. The case of Dr. Spock is one of many in Helen's book, where the received wisdom did not match up with the evidence. And in many cases, the evidence is not nearly as clear. But even when you've got good evidence, that doesn't mean it's going to be accepted. One reason that evidence is very difficult to accept is that often it shows that what people have been doing is wrong and it's very difficult to accept that you were wrong and particularly difficult if it means that it has contributed to harm to other people. Thanks to Helen Pearson, author of Beyond Belief, how evidence shows what really works. If you've seen a number or some childcare advice you think we should look at, email more or less at bbc.co.uk. Until next week, goodbye.
