BABY boxes were "fundamental" in cutting cot deaths among vulnerable babies in New Zealand but the high-sided design used in Scotland "has nothing to do with saving lives", one of the world's leading experts on infant mortality has said.

Professor Ed Mitchell said the deep Finnish-style design meant that parents would not be able to see or feel their baby if it was sleeping in the box in bed with them, unlike the shallower plastic Pepi-Pod or woven baby boxes given to some parents in New Zealand.

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Prof Mitchell, who was in Glasgow for the International Conference on Stillbirth, SIDS and Baby Survival, added that he "didn't see the point" in giving baby boxes to all families, regardless of wealth.

In a five-year period from 2010 to 2014, New Zealand cut cot deaths by 30 per cent. This coincided with the rollout of wahakura - woven baby boxes - and plastic pepi-pods, designed to make it safer for parents to bed-share with their baby, and to boost breastfeeding rates.

The initiative followed concerns about high rates of cot death in the Maori community in particular - which was five-fold that of Kiwis with European ancestry - partly because bed-sharing was a cultural norm.

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The shallow-style baby boxes meant parents could still see their infant easily while sharing a bed, but would be blocked from rolling onto them.

Prof Mitchell, of the University of Auckland, said: "This has been fundamental. The biggest thing that happened is we stopped talking about [cot death] as something unavoidable or unpredictable.

"Accidental suffocation is preventable, and it's amazing how much of a difference that has made to being able to talk to parents about safe sleeping."

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However, he said Scotland's baby box policy was "very different".

He said: "The baby box that Scotland is getting is a nice gift for the family, but it has nothing to do with saving lives.

"With the pedi-pod or wahakura, the sides are so shallow you can reach around and see and feel the baby, although it's in a separate space.

"With the Finnish-style model used in Scotland, although it's been designed for babies to sleep in, the big high sides make it almost impossible for the parents to use it in bed with them so I don't think it's going to be beneficial in terms of reducing SUDI [sudden unexpected deaths in infancy]."

Prof Mitchell said the boxes should be targeted to at-risk infants. The risk of cot death is higher among babies whose mothers smoked in pregnancy, who are not breastfed, are low birth-weight and whose parents smoke, drink or abuse drugs.

Canadian academic Professor Karen Benzies said a programme in Alberta which provided vulnerable first-time parents with a Finnish-style baby box, parental education and mentoring had reduced rates of postnatal depression, but not cot deaths.

She criticised authorities - including some parts of North America - which had promoted baby boxes as a lone tool to cut infant mortality.

Prof Benzies said: "Until the evidence is clear, we should avoid distributing baby boxes alone, without concomitant health and social care supports, with the aim of reducing SUDI."

The Scottish Government has previously said its baby box offers a safe sleeping place when used in accordance with other safe sleeping practices.