The rate of infant deaths affecting mothers under the age of 20 increased from 0.92 to 1.27 per 1,000 births between 2012 and 2013.
Figures published by the Office for National Statistics (ONS) today show that across England and Wales in 2013 there were 249 unexplained infant deaths, a rate of 0.36 per 1,000 live births.
This is up on the 2012 rate of 0.32 and comes after five years of falls since 2008, when the rate was 0.41.
See more at: Unexplained infant deaths rise for first time in five years.