The infant mortality rate in England and Wales continues to fall. In 2011, there were just 4.2 infant deaths per 1,000 live births – the lowest rate on record. This compares with 11.1 deaths in 1981, a 62% decrease. An infant death is defined as the death of a child less than 1-year-old.
Figure 1: Infant mortality rates in England and Wales, 1981 to 2011
In the chart above, neonatal mortality covers deaths of infants less than 28-days-old, whereas postneonatal mortality covers deaths from 28-days-old to one year. Both these measures are reflected in the infant mortality rate.
Low birthweight is a major risk factor
The highest rates of infant mortality in England and Wales in 2011 were among women aged 40 and over, with 5.5 deaths per 1,000 live births. Women under the age of 20 had the second highest infant mortality rate with 5.4 deaths per 1,000 live births.
In addition to age, other risk factors for infant mortality include low birthweight and multiple births. These risk factors are related; for instance, older women are more likely to have multiple births, which increases the likelihood of the babies being of low or very low birthweight, which increases the risk of death during the first year of life.
In 2011, there were 172.6 deaths per 1,000 live births for very low birthweight babies (under 1,500 grams) and 36.5 deaths per 1,000 live births for low birthweight babies (under 2,500 grams). This compares with a rate of 1.4 deaths per 1,000 live births among babies of normal birthweight (over 2,500 grams).
Smoking is a major risk factor contributing to low birthweight. For the UK as a whole, mothers under the age of 20 had the highest levels of smoking (57%) before or during pregnancy in 2010. They were also almost six times as likely as mothers aged 35 or over to have smoked throughout pregnancy (35% and 6% respectively) (Health and Social Care Information Centre, 2012).
The infant mortality rate for multiple births is five times higher than for single births. On average, multiple birth babies tend to have a lower birthweight than single birth babies, which is one reason why the infant mortality rate is higher for this group.
Just over half of multiple birth babies (55%) were of low birthweight, compared to 5.5% of single babies. Although multiple births occur naturally, many occur as a result of fertility treatment. Approximately 25% of in vitro fertilisation (IVF) pregnancies result in either twins or triplets compared with 1% of pregnancies conceived naturally (HFEA). Nearly two-thirds of all multiple babies in 2011 were born to women aged 30 years or over.
Significant differences in infant mortality by socio-economic group persist in England and Wales. Infant mortality rates were highest for babies with fathers employed in semi-routine occupations (for example, shop assistants or care assistants). This may be caused by a link between deprivation, poor maternal health and low birthweight.
An historical perspective
In England and Wales, 130 out of every 1,000 children born in 1911 died before their first birthday. The decrease in infant deaths over the past century is due to advances in healthcare, including the control of infectious diseases and improved public health infrastructure, as well as specific improvements in midwifery and neonatal intensive care.
For the UK as a whole, infant mortality has been declining and is now only about a quarter of what it was in 1970. The rate is currently similar to the average rate of countries inside the Organisation for Economic Co-operation and Development.
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