Statistical bulletin: Infant and perinatal mortality in England and Wales by social and biological factors, 2009

Key points

• In 2009 the infant mortality rate was 4.4 per 1,000 live births, the lowest recorded for England and Wales.
• Infant and perinatal mortality rates were highest for very low birthweight babies (under 1,500 grams).
• Babies of mothers aged under 20 had the highest infant mortality rate at 6.0 deaths per 1,000 live births.
• Infant mortality was highest for babies registered jointly by parents living at different addresses and those registered solely by mother.

Introduction

This bulletin on infant and perinatal mortality presents statistics on infant deaths and births that occurred in 2009. The report focuses on the 98 per cent of infant deaths which have been successfully linked to their corresponding birth records (see Background note 2). This linkage enables analysis of infant and perinatal deaths by risk factors collected at birth registration. These include birthweight, mother's age at birth of child, mother's country of birth, marital status, parity and father's socio-economic status based on his occupation.

Results

In 2009 of all linked infant deaths, 2,177 (69.3 per cent) occurred during the first 28 days of life (neonatal deaths) and 964 (30.7 per cent) between 28 days and one year (postneonatal deaths)

( Table 1 (368 Kb Excel sheet) ). The infant mortality rate (IMR) was 4.4 per 1,000 live births, with the neonatal mortality rate over twice the postneonatal rate (3.1 and 1.4 per 1,000 live births respectively). From 1999 to 2009 the IMR decreased by a fifth, from 5.7 to 4.4 per 1,000 live births.

 The IMRs for very low birthweight babies (under 1,500 grams) and low birthweight babies (under 2,500 grams) were 175.9 and 38.3 per 1,000 live births respectively, while the rate for normal birthweight babies (2,500 grams and over) was 1.5 per 1,000 live births ( Table 2 (368 Kb Excel sheet) ). Perinatal and neonatal mortality rates were also highest in the very low birthweight category (256.2 per 1,000 total births and 141.6 per 1,000 live births respectively).

 For stillbirths, the majority of very low birthweight babies (under 1,500 grams) were also of low gestational age (24–27 weeks) ( Table 3 (368 Kb Excel sheet) ). Most stillbirths (67 per cent) were preterm (less than 37 completed weeks of gestation). Additionally, of all preterm stillbirths, 63.8 per cent belonged to the very low birthweight category.

 Infant death rates also varied by mother’s age at the time of birth of the baby ( Table 4 (368 Kb Excel sheet) ). The IMR was highest among babies of mothers aged under 20 (6.0 per 1,000 live births) and lowest among babies with mothers in the 30–34 age group (3.9 per 1,000 live births). Babies of mothers aged 40 and over had the highest stillbirth and perinatal mortality rates at 7.7 and 10.6 per 1,000 total births respectively.

  Table 5 (368 Kb Excel sheet) shows births and infant deaths by mother’s country of birth (see Box 1 (368 Kb Excel sheet) for country groupings). The IMR was 50 per cent higher for babies of mothers born in the New Commonwealth compared with babies of mothers born in England and Wales (6.3 and 4.2 per 1,000 live births respectively). Within the New Commonwealth, the IMR was highest for babies of mothers born in East Africa (8.9), the Caribbean (8.4) and Pakistan (7.9): all rates are deaths per 1,000 live births.

 The perinatal mortality rate was also higher in babies of mothers born in the New Commonwealth compared with babies of mothers born in England and Wales (10.5 and 7.2 per 1,000 total births respectively). Within the New Commonwealth, the perinatal mortality rate was highest in babies of mothers born in the Caribbean (13.5 per 1,000 total births).

 The registration types with the highest IMR were births outside marriage registered jointly by both parents living at different addresses (5.6 per 1,000 live births), and births registered solely by the mother (5.5 per 1,000 live births) ( Table 6 (368 Kb Excel sheet) ). The perinatal mortality rate was highest among sole registered births (6.8 per 1,000 total births).

 Parity – the total number of births a woman has had previously – is only recorded for married women. The IMR was highest among mothers with three or more previous children (6.1 per 1,000 live births).

  Table 7 (368 Kb Excel sheet) shows infant deaths by father’s occupational status (see Box 2 (368 Kb Excel sheet) for occupational classes). Outside marriage, the IMR was highest for babies with fathers in semi-routine occupations (5.6 per 1,000 live births). The highest rates for stillbirths and perinatal deaths occurred among the ‘other’ category. This category comprises a mixed group including never worked; long term unemployed, students and those individuals whose occupational details could not be classified. Therefore these figures should be interpreted with caution because the rates may vary between the different sub-groups.

 In England and Wales, stillbirths and neonatal deaths are registered using a special 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 using the standard death certificate. ONS has developed a hierarchical classification system producing broad cause groups to enable direct comparison of neonatal and postneonatal deaths (Dattani & Rowan, 2002). Table 8 (368 Kb Excel sheet) shows that factors operating during pregnancy (congenital anomalies, antepartum infections and immaturity related conditions) were the most common cause of infant and neonatal deaths (73.6 and 85.3 per cent respectively). For postneonatal deaths less than half were related to factors operating during pregnancy (47.0 per cent); while 19.3 per cent were ‘other conditions’; 14.4 per cent were sudden infant deaths; and 12.4 per cent were from infections. The majority of stillbirths were classified as antepartum deaths (72 per cent).

Box one - Mother's Country of birth

United Kingdom

England, Wales, Scotland, Northern Ireland

Elsewhere in United Kingdom

Channel Islands, Isle of Man, UK (part not stated)

Outside United Kingdom

Irish Republic

Irish Republic, Ireland (part not stated)

Other European Union

Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Luxembourg, Malta, The Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden

Rest of Europe

All other European countries including Turkey, Russia, Ukraine and the rest of the former Soviet republics.

Commonwealth

Australia, Canada, New Zealand

New Commonwealth:

Asia: Bangladesh, India, Pakistan

East Africa: Kenya, Malawi, Mozambique, Tanzania, Uganda, Zambia

Southern Africa: Botswana, Lesotho, Namibia, South Africa, Swaziland

Rest of Africa: Cameroon, The Gambia, Ghana, Mauritius, Nigeria, Seychelles, Sierra Leone

Far East: Brunei, Malaysia, Singapore

Caribbean: Anguilla, Antigua, Bahamas, Barbados, Belize, Bermuda, British Virgin Islands, Cayman Islands, Dominica, Grenada, Guyana, Jamaica, Montserrat, St Kitts and Nevis, St Lucia, St Vincent, Trinidad and Tobago, Turks and Caicos Islands

Rest of the New Commonwealth

Cook Islands, Falkland Islands, Fiji, Gibraltar, Kiribati, Maldives, Nauru, Papua New Guinea, St Helena, Solomon Islands, Sri Lanka, Tonga, Tuvalu, Vanuatu, Western Samoa, British Indian Ocean Territory

United States of America

Rest of the World and not stated

Box Two - National Statistics Socio-economic Classification (NS-SEC): eight analytic class version, with examples

1 Higher managerial and professional occupations

Directors and chief executives of major organisation, civil engineers, medical practitioners, IT strategy and planning professionals, legal professionals, architects, senior officials in national and local government

2 Lower managerial and professional occupations

Teachers in primary and secondary schools, quantity surveyors, public service administrative professionals, social workers, nurses, IT technicians

3 Intermediate occupations

Graphic designers, medical and dental technicians, Civil Service administrative officers and local government clerical officers, counter clerks, school and company secretaries

4 Small employers and own account workers

Hairdressing and beauty salon proprietors, shopkeepers, dispensing opticians in private practice, farmers, self-employed decorators

5 Lower supervisory and technical occupations

Bakers and flour confectioners, catering supervisor, head waitress, postal supervisor, sales assistant supervising others

6 Semi-routine occupations

Retails assistants, catering assistants, clothing cutters, dressmaker, traffic wardens, veterinary nurses and assistants, shelf fillers

7 Routine occupations

Hairdressing employees, floral arrangers, sewing machinists, bar staff, cleaners and domestics

Other

Full-time students, never worked, long-term unemployed, inadequately described, not classifiable for other reasons

Source: NS-SEC User Manual, Office for National Statistics (Office for National Statistics 2001, see references)

Background notes

1. Definitions used in infant mortality statistics:

Stillbirth – born after 24 or more weeks completed gestation and which did not, at any time, breathe or show signs of life

Early neonatal – deaths under seven days

Perinatal – stillbirths and early neonatal deaths

Neonatal – deaths at under 28 days

Postneonatal – deaths between 28 days and one year

Infant – deaths under one year

Rates – stillbirths and perinatal mortality rates reported per 1,000 total births (live and stillbirths). Neonatal, postneonatal and infant mortality rates are reported per 1,000 live births.

 2. The figures for 2009 presented in this report relate to live births, stillbirths and infant deaths that occurred in England and Wales in that year and comprise the infant deaths which had been linked to their corresponding birth records. In 2009 there were 3,193 infant deaths in England and Wales of which 3,141 (98 per cent) were linked. Of the 52 records that were not linked, 28 babies were born outside England and Wales (and therefore not registered in England and Wales) and 24 were not linked because no record of the birth could be found. The linkage rate for 2009 is comparable with that for previous years.

3. This report is based on data available up to 20 September 2010 and figures for 2009 are provisional. Figures reported in Table 1 for 1999 to 2008 are final.

4. Details of the associated ICD–10 codes allocated to stillbirths, neonatal deaths and postneonatal deaths can be found in Annex J, K and L respectively and a description of the ONS cause group classification system on page xix of Mortality statistics: Childhood, infant and perinatal, 2007, Series DH3 no. 40.

References

1.   Dattani N and Rowan S (2002) ‘Causes of neonatal deaths and stillbirths: a new hierarchical classification in ICD–10’, Health Statistics Quarterly 15, 16–22. 

2. Office for National Statistics (2001) The National Statistics Socio–economic Classification.

Background notes

1. Details of the policy governing the release of new data are available from the Media Relations Office. National Statistics are produced to high professional standards set out in the Code of Practice for Official Statistics. They ubdergo regular quality assurance reviews to ensure that they meet customer needs. They are produced free from political interference.

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2. Details of the policy governing the release of new data are available by visiting www.statisticsauthority.gov.uk/assessment/code-of-practice/index.html or from the Media Relations Office email: media.relations@ons.gsi.gov.uk