"Figure 4: Infant mortality rates for single and multiple births by age of mother at birth and term, 2008-2012 birth cohorts","" "England and Wales (1),(2),(3)","" "","" "Notes","1. Pre-term is 24 to 36 completed weeks, term is 37 to 41 completed weeks. 2. Known gestational age only. 3. Infant mortality rates per 1,000 live births." "Unit","Rate per 1,000 live births" "","" "","Single pre-term","Multiple pre-term","Multiple term","Single term" "Under 20","31.8","49.9","4.7","2.3" "20-24","30.0","31.0","4.8","1.8" "25-29","25.3","22.8","2.9","1.5" "30-34","24.6","21.8","1.8","1.3" "35-39","24.3","19.1","2.3","1.3" "40+","27.8","20.4","2.7","2.1"