Enzyme in babies’ blood linked to risk of sudden infant death syndrome

The British scientist whose work underpinned the Back to Sleep campaign of the 1990s has hailed the study as a significant advance in the search for the causes of sudden infant death syndrome.

cot death, also known as Sids, is when an apparently healthy infant dies during their sleep, and the study found a marker in the blood that is linked to the risk. The test isn't accurate enough to be used in newborn screening, but it shows that low levels of a chemical linked to the brain could be involved in sudden infant death syndrome.

Prof Peter Fleming of the University of Bristol is credited with preventing tens of thousands of UK baby deaths after the Back to Sleep campaign launched in the 1990s.

The investigation was led by Dr Carmel Harrington, who lost her own son to Sids 29 years ago. The dried blood samples were compared to see if there were any babies who died from Sids and if there were any babies who died from other causes.

They found that the Sids babies had lower levels of an important brain chemical. An arousal deficit could be a sign that an infant is not able to wake up or respond to the outside environment. Scientists said this could cause vulnerability to Sids.

We didn't know what was causing the lack of arousal.

Until now, there was no way to know which baby would die if they didn't wake up.

Testing for BChE wouldn't be helpful as a newborn screening tool. Although the Sids babies had lower levels on average, there was also a lot of overlap between the groups, with about half of the Sids babies falling within the same range as half of the babies who did not die.

Smoking during pregnancy is linked to a more than threefold increase in Sids incidence, but the biomarker is not as powerful a predictor. Babies with low BChE had a higher risk of Sids.

The thing that worries me is that it isn't usable by the individual.

The findings could help explain how smoking in pregnancy leads to biological changes that put babies at greater risk of Sids.

The findings of the study are interesting and more work needs to be done, said Jenny Ward, the chief executive of the Lullaby Trust. We hope that this research will help us understand sudden infant death syndrome.

She said that the findings should not be seen as a reason to downplay safer sleep advice, such as always sleeping baby on their back in a clear sleep space on a flat, firm and waterproof mattress with no bulky bedding, pillows or cot bumpers.

The findings are published in a journal.