I have been asked to reply.
The information requested falls within the responsibility of the UK Statistics Authority. I have asked it to reply.
Letter from Jil Matheson, dated September 2009:
As National Statistician, I have been asked to reply to your recent question asking what the most common cause of infant mortality is. (291646)
Infant mortality is defined as death under one year after live birth, and can be divided into neonatal deaths (less than 28. days after live birth) and postneonatal deaths (28 days but under one year). In England and Wales, neonatal deaths are registered using a special perinatal death certificate which enables reporting of relevant diseases or conditions in both the infant and the mother. For postneonatal deaths, a single underlying cause of death can be reported as for adults. ONS has developed a classification system producing broad cause groups to enable direct comparison of neonatal and postneonatal deaths.
Using this ONS classification, the most common cause of infant deaths is ‘Immaturity related conditions’. This includes certain respiratory, cardiovascular and other conditions related primarily to the prematurity or low birthweight of the infant. In 2007 (the latest year for which figures are available), there were 1,346 infant deaths coded to ‘Immaturity related conditions’, 42 per cent of all infant deaths in England and Wales in that year.