1. Introduction

We produce infant mortality statistics that are published under the National Statistics logo, the designation guaranteeing that those outputs have been produced to high professional standards set out in the Code of Practice for Statistics and have been produced free from any political interference.

This page provides information on the collection, production and quality of mortality data for:

  • Child mortality (death cohort) tables, which present final statistics on stillbirths, infant deaths and childhood deaths that occurred in England and Wales in a calendar year

  • Infant mortality (birth cohort) tables, which present final statistics on births and infant deaths based on babies born in a calendar year that died before their first birthday linked to their corresponding birth notification and their corresponding death registration

The Child and infant mortality statistics Quality and Methodology Information report contains important information on:

  • the strengths and limitations of the data

  • the quality of the output: including the accuracy of the data and how it compares with related data

  • uses and users

  • how the output was created

The User guide to birth statistics provides information on the collection, production and quality of birth statistics based on birth registration data.

Following the results of the infant mortality user consultation, carried out in spring and summer 2017, we will continue to produce Child mortality statistics and have combined Birth cohort tables for infant deaths and the Pregnancy and ethnic factors influencing births and infant mortality into one publication called Infant mortality (birth cohort) tables. There have been revisions to both sets of tables to improve presentation and to meet our user needs, details of which are available in the response to the consultation.

The Office for National Statistics policy on protecting confidentiality in birth and death statistics is also available.

Back to table of contents

2. Occurrences and registrations

Deaths

The annual total of deaths occurring in a calendar year is taken from the standard dataset for death occurrences created from the deaths database. To be acceptably complete, this annual extract must be taken some months after the end of the data year to allow for late death registrations. Although there will inevitably be a small number of deaths not registered when the annual extract of death occurrences is taken, delaying the timing of the extract any further will delay the publication of the data.

The Child mortality (death cohort) tables represent figures and rates on stillbirths, infant deaths (under 1 year of age) and childhood deaths (between 1 and 15 years of age) occurring annually in England and Wales. Where relevant, infant deaths are linked to their corresponding birth records to enable analysis of risk factors and demographic characteristics collected at birth registration.

The Infant mortality (birth cohort) tables represent those babies born in a calendar year who died before their first birthday linked to their corresponding birth notification and their corresponding death registration.

Births

The annual totals of live births and stillbirths are derived from the standard annual extract of live births and stillbirths. This extract includes all births occurring and registered in a calendar year plus late registrations from the previous year.

Back to table of contents

3. Childhood and infant deaths

In Child mortality (death cohort) tables, childhood deaths are defined as between 1 and 15 years of age. Infant deaths (under 1 year) at various ages are defined as:

Embed code

3.1 Stillbirths

The Stillbirth (Definition) Act 1992 defines a stillbirth as:

“a child which has issued forth from its mother after the twenty-fourth week of pregnancy, and which did not at any time after becoming completely expelled from its mother breathe or show other signs of life”.

This definition has been in use since 1 October 1992. Prior to this, the Births and Deaths Registration Act 1953 defined a stillbirth as in the 1992 Act, but at 28 or more weeks completed gestation. Figures for stillbirths from 1993 are thus not comparable with those for previous years. The effect of this change on figures for 1992 is analysed in the annual volume of birth statistics for that year (Office of Population, Censuses and Surveys 1994).

3.2 Registration and certification of stillbirths, neonatal and infant deaths

General information about the registration and certification of stillbirths, neonatal and infant deaths in England and Wales can be found in the User guide to mortality statistics. It also provides information about the specific details collected when a death is certified and registered.

3.3 Death rates

The rates presented in these publications are:

  • Stillbirth rate:


  • Perinatal mortality rate:


  • Early neonatal mortality rate:


  • Neonatal mortality rate:


  • Postneonatal mortality rate:


  • Infant mortality rate:


  • Age-specific child mortality rate:


Back to table of contents

4. Referral to the coroner

While the majority of infant deaths are certified by a doctor, some may be reported to the coroner by the certifying doctor or the registrar. The circumstances under which a death has to be referred are covered in the User guide to mortality statistics.

Table 1 provides the numbers of deaths by method of certification for those infants aged under 1 year, in 2017. Stillbirths may be certified by the medical practitioner or the midwife who is present at or who conducts the delivery, or who examines the body after birth. In 2017, 71% were certified by midwives and 26% by doctors.

The conditions for certifying neonatal deaths are as for other deaths – that the doctor should have been in attendance during the deceased’s last illness, should have seen the patient prior to death or seen the body, and that the cause of death is known and is “natural”.

Inquests on stillbirths and neonatal deaths are rare. In 2017, 86% of neonatal deaths were certified by a doctor and 13% by a coroner with only 5% subject to a coroner’s inquest. This reflects the fact that nearly all neonatal deaths occur in hospitals and that infant deaths can be certified as due to sudden infant death syndrome (SIDS) without being subject to inquest.

Back to table of contents

5. Area coverage and base populations

5.1 Area coverage

The births and deaths recorded in the annual publication Child and infant mortality statistics are those occurring in a given calendar year, which have been registered in England and Wales.

Births and deaths to residents of England and Wales that occur and are registered outside of England and Wales are excluded. Births and deaths registered in England and Wales to persons whose usual residence is outside England and Wales are included in any total figures for England and Wales, but are excluded from any sub-division of England and Wales. Figures for live births and stillbirths to women whose usual residence is outside of England and Wales can be found in Tables 5 and 6 in the publication Birth characteristics.

Table 2 gives recent numbers of infant deaths that occurred in England and Wales in a given year for those infants not usually resident in England and Wales.

5.2 Base populations

The population figures used to calculate child mortality rates are mid-year estimates of the resident population of England and Wales based on the Census of Population. The Office for National Statistics mid-year population estimates are based on updates from the most recent census allowing for births, deaths, net migration and ageing of the population.

The population estimates used for the calculation of mortality rates are the latest consistent estimates available at the time of production. Further information on population estimates and their methodology is also available.

Back to table of contents

6. Coding the underlying cause of death

For deaths at ages 28 days and over, the death certificate (Annex D) used in England and Wales accords with that recommended by the World Health Organisation (WHO) in the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) (WHO 1992 to 1994). Further information regarding coding the underlying cause of death can be found in the User guide to mortality statistics.

On 1 January 2014, the Office for National Statistics (ONS) changed the software used to code cause of death from MMDS to IRIS. The new IRIS software version 2013 incorporates official updates to ICD-10 that are approved by WHO. The use of the IRIS software has helped to improve the international comparability of mortality statistics.

One impact of this has been that for stillbirths and neonatal deaths, any maternal condition mentioned on the death certificate are coded to the chapter XVI (certain conditions originating in the perinatal period) rather than elsewhere in the ICD classification. Previously these deaths may have been coded to the chapter XV (pregnancy, childbirth and the puerperium).

Further information on IRIS is available. There is also a study that looks into the impact of the coding changes on stillbirths and neonatal deaths.

6.1 Neonatal and stillbirth cause of death certificates

The neonatal and stillbirth certificates (Annex D), introduced in January 1986 follow recommendations of WHO in the ICD, whereby causes of death are given separately in the following categories:

  • main diseases or conditions in infant/fetus

  • other diseases or conditions in infant/fetus

  • main maternal diseases or conditions affecting infant/fetus

  • other maternal diseases or conditions affecting infant/fetus

  • other relevant causes

While conditions arising in the mother that affected the infant could be mentioned on certificates prior to 1986, no provision was made for those cases in which the certifier considered that both maternal and infant conditions contributed to the death. The current certificates overcome this problem. However, since equal weighting is given to main conditions in the infant and in the mother, it is no longer possible to identify a single underlying cause of death for neonatal deaths and stillbirths.

6.2 ONS cause of death groups

In England and Wales, stillbirths and neonatal deaths are registered using a special death certificate (Annex D), 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.

The ONS has developed a hierarchical classification system (PDF 72KB) producing broad cause groups to enable direct comparison of neonatal and postneonatal deaths. The hierarchical classification, which is referred to as the ONS cause groups allows the death to be assigned to a specific category, based on the likely timing of the damage leading to the death. A computer algorithm directs any mention, in the case of neonatal deaths, and underlying cause in the case of postneonatal deaths, to the first appropriate class of the following mutually exclusive categories:

Before the onset of labour

1 Congenital anomalies
2 Antepartum infections
3 Immaturity-related conditions

In, or shortly after labour

4 Asphyxia, anoxia, or trauma

Postnatal

5 External conditions
6 Infections
7 Other specific conditions
9 Sudden infant deaths

Unclassified

0 Other conditions

A similar algorithm is used for stillbirths.

The grouping of ICD-10 codes into these nine categories for neonatal and postneonatal deaths is shown in Annexes B and C respectively. Corresponding groupings for stillbirths are shown in Annex A. (Annexes A.1, B.1 and C.1 refer to 2001 to 2010, Annexes A.2, B.2 and C.2 refer to 2011 to 2013 and Annexes A.3, B.3 and C.3 refer to 2014 onwards.)

However, for the data years 2001 to 2012, postneonatal deaths were assigned to the ONS cause groups based on mentions rather than underlying cause. Some analysis of the impact of this change in methods is available on request.

Back to table of contents

7. Linkage of births and deaths

Since 1975, infant death records have been linked to their corresponding birth record. This is because the birth record includes a considerable amount of information about parent(s) that the death record does not. Therefore, we carry out this linkage as it enables analysis of risk factors and demographic characteristics. This includes: age of each parent, number of previous children born to the mother, country of birth of parents, place of birth and whether the baby was a singleton or multiple birth.

The unlinked cases can be split into two groups: those that cannot be linked (such as those born outside England and Wales, foundlings, and adopted children) and others that should have been linked but for which no birth registration record could be found. Around 2% of infant deaths cannot be linked to a birth registration record.

7.1 Socio-economic classification as defined by occupation

For the child and infant mortality publications, the information on occupation and employment is used to derive National Statistics Socio-economic Classification (NS-SEC). To be able to do this, the occupation information of parent(s) from birth and death certificate must first be coded. For death certificates for infant deaths and stillborn babies, this coding is completed for all records. However, for live births, only 10% are coded as this is deemed sufficient quality for statistical analysis.

It does mean that for any tables that include NS-SEC based on the occupation information from live birth certificates, the figures shown are calculated by grossing up the breakdowns for the 10% of records that have been coded by a factor of 10. As a result, this means the sum of the NS-SEC breakdowns do not match the grand total, which is based on the full birth and death extracts.

From 1991 to 2000, occupation was coded using the Standard Occupational Classification SOC 90, and occupation codes were allocated to the Registrar General’s Social Class. Since 2001 the National Statistics Socio-economic Classification (NS-SEC) has categorised the socio-economic classification of people.

The Standard Occupational Classification is revised every 10 years and in 2011 SOC 2010 replaced SOC 2000. A report outlining the impact of re-basing the NS-SEC on SOC 2010 is available.

NS-SEC has eight analytic classes, the first of which can be subdivided:

1 Higher managerial and professional occupations
1.1 Large employers and higher managerial occupations
1.2 Higher professional occupations

2 Lower managerial and professional occupations

3 Intermediate occupations

4 Small employers and own-account workers

5 Lower supervisory and technical occupations

6 Semi-routine occupations

7 Routine occupations

8 Never worked and long-term unemployed

Students, occupations not stated or inadequately described, and occupations not classifiable for other reasons are added as “Not Classified”.

NS-SEC also has three analytic classes:

1 Higher managerial, administrative and professional occupations

2 Intermediate occupations

3 Routine and manual occupations

The number of classes you use will depend on both your analytic purposes and the quality of available data.

Up until the 2011 data year, the ONS published child mortality and birth statistics by NS-SEC using the father’s NS-SEC. Historically, the decision to use father’s NS-SEC was based on the premise that many mothers either do not have a paid occupation or choose not to state their occupational details at birth registration.

From the 2012 data year, the ONS has used the combined method for reporting NS-SEC for birth and child mortality statistics (using the most advantaged NS-SEC of either parent and creating a household-level classification rather than just using the father’s classification). More information can be found in a report on the combined method.

7.2 Births within or outside marriage or civil partnership, and sole and joint registration

Since 1 September 2009, following the implementation of the Human Fertilisation and Embryology Act (2008), same-sex female couples have been able to register the birth of a child as mother and second parent. The Act also made provision for two men to be officially recognised as the parents of a child through the provision of a parental order, obtainable through the courts.

Due to small numbers, births registered within a civil partnership are included with births registered within marriage. Births registered to a same-sex couple outside of a civil partnership are combined with births outside marriage. Given the relatively small numbers of births registered to same-sex couples, the impact on statistics is negligible.

A birth within marriage or civil partnership is that of a child born to parents who were lawfully married or in a civil partnership either:

  • at the date of the child’s birth, or

  • when the child was conceived, even if they later divorced or were granted a civil partnership dissolution, or the father or second parent died before the child’s birth

Births occurring outside marriage or civil partnership may be registered either jointly or solely. A joint registration records details of both parents and requires them both to be present. A sole registration records only the mother’s details. In a few cases a joint registration is made in the absence of the father or second parent if an affiliation order or statutory declaration is provided.

Information from the birth registration is used to determine whether the mother and father or second parent jointly registering a birth outside marriage or civil partnership were usually resident at the same address at the time of registration. Births with both parents at the same address are identified by a single entry for the informant’s usual address, while different addresses are identified by two entries.

Some infants born outside marriage are deemed to have been born within marriage when the natural parents subsequently marry between the infant’s birth and death. Birth registrations do not, however, identify children whose parents marry after the birth of the child. All relevant tables in Child mortality (death cohort) tables and Infant mortality (birth cohort) tables relate to marital status at birth. This ensures that the numerators and denominators used to calculate rates are compatible.

7.3 Mother’s country of birth

The birthplace of the parents of children born in England and Wales has been recorded at birth registration since 1969, but these data have only been available for an infant mortality analysis of social factors since 1975, when routine linkage was started. A breakdown of the mother’s country of birth groupings can be found alongside the published tables.

7.4 Birthweight

Birthweight is measured in grams. For live birth registrations, the birthweight is passed electronically to the ONS from the notification by the midwife or doctor in attendance at the birth. These details are then supplied to the registrar. For stillbirths, details of the weight of the fetus are supplied on a certificate or notification by a doctor or midwife. The certificate or notification is then taken by an informant to the registrar.

If the birthweight is missing, but the registration is linked to the birth notification, then the birthweight from the notification is taken. In cases where no birthweight is recorded, the birth is included in the total “all weights” but not distributed among the individual categories. Any remaining missing birthweights are included in the “Not stated” total for the relevant tables containing birthweight. Annual figures for records where the birthweight was not recorded for live births and stillbirths can be found in the User guide to birth statistics.

7.5 Number of previous children

In May 2012, the ONS implemented a legislative change to improve the statistical information collected at birth registration in England and Wales. Two amendments have been made to the Population (Statistics) Act 1938, the legislation that requires registrars to collect confidential information for statistical purposes. The changes were made within the Welfare Reform Act 2009.

The two amendments mean that:

  • information is now collected at all birth registrations on the total numbers of previous live births and previous stillbirths that the mother has had (not just those with the current or former husband); this has simplified the question asked by registrars and provide improved coverage

  • information is now collected at all birth registrations on either:

    • whether the mother has been previously married or in a civil partnership (if she is currently married or in a civil partnership) or
    • whether the mother has ever been married or in a civil partnership (if she is not currently married or in a civil partnership)

This brings the birth registration process more in line with equality legislation.

Prior to May 2012, information on:

  • number of previous children with a current or former husband

  • whether the mother had previously been married

was only collected for births occurring within marriage. When the Population (Statistics) Act came into force in 1938, only 4% of live births in England and Wales occurred outside marriage so the information required was collected for nearly all mothers. However, by 2011 nearly half of births (47%) took place outside marriage or civil partnership and so the legislation no longer reflected the reality of modern society.

Only minor changes have been made to published tables for 2012 and 2013 since the first full year of new data is 2013 but some childhood deaths in this year will relate to births in 2012 prior to the changes being implemented. The main improvements resulting from the amendments to the Population (Statistics) Act 1938 have been introduced to published tables for child deaths occurring in 2014. Figures for 2014 onwards are not comparable with previous years.

Although tables affected by the amendments to the Population (Statistics) Act 1938 were published for child deaths occurring in 2012 and 2013, there was a small definitional change in the data following implementation. Up to late May 2012, previous children include only those with a current or former husband, while after late May 2012 all previous children should be counted. This was not expected to have made a large difference to the figures as it was not clear how accurately the original question was understood or answered.

7.6 Gestation

Gestational age is measured in completed weeks. For stillbirths, gestation is recorded at birth registration and is therefore available on our annual births datasets. For live births and infant deaths, gestation is not recorded on the birth registration. For this reason gestation for live births and infant deaths is only available on our annual linked deaths dataset where birth registrations have been successfully linked to birth notifications, which does record the gestational age.

Embed code

7.7 Mother’s age

For 2013 to 2017, if the mother’s age was missing, it was imputed using the most recently processed complete record of similar characteristics to the incomplete record due to the very small number of records requiring imputation. However, the improvement of these imputations on the quality of the statistics was unclear given the small number of records this affects. As such, imputation was discontinued in March 2018 to make processing more efficient and our methods easier for users to understand, without any negative effect on accuracy. The remaining records where mother’s age is missing will now be categorised as “not stated” in our tables.

Back to table of contents

8. Further information

Our website (www.ons.gov.uk) provides a comprehensive source of freely available vital statistics and Office for National Statistics (ONS) products. More information on our website can be obtained from the contact addresses in this section.

Special extracts and tabulations of child mortality data for England and Wales are available to order (subject to legal frameworks, disclosure control, resources and our charging policy, where appropriate). Such enquiries should be made to Vital Statistics Outputs Branch (vsob@ons.gov.uk or telephone: +44 (0)1329 444 110). All user requested data will be published onto the website.

8.1 Other sources of information on births and deaths

Additional information on background to mortality data that we publish, together with the quality of mortality data can be found in sections 16 and 12 of the User guide to mortality statistics. Further information and background on birth statistics can be found in the User guide to birth statistics.

8.2 Other sources of data on births and deaths

Deaths occurring in a given year

Deaths registered in a given year

Summary data for infant mortality in England and Wales are available in the Deaths registrations summary tables. A geographical breakdown of infant death numbers and rates by local authority and county level is available in Deaths registered in England and Wales by area of usual residence.

The Vital statistics in the UK: births, deaths and marriages provide annual infant mortality data for the United Kingdom and its constituent countries.

Other UK countries

For mortality data for other UK countries please see the latest infant death statistics for Northern Ireland and the latest infant death statistics for Scotland.

Births

The Births summary tables, England and Wales provide key summary statistics for live births in England and Wales.

8.3 Other useful information

We welcome feedback from users on the content, format and relevance of mortality outputs.

Back to table of contents

9. Glossary

Antepartum

Occurring just before birth.

Cause groups

The ONS cause groups is another term used for “Hierarchical classification”; see following entry.

Childhood

Children aged between 1 and 15 years.

Congenital anomaly

A structural or functional abnormality of the human body that develops before birth.

Coroner

Public official responsible for the investigation of violent, sudden or suspicious deaths.

Early neonatal

Relating to infants aged under 7 days.

Hierarchical classification

ONS’s method for classifying the causes of neonatal deaths and stillbirths, made up of groups of ICD codes referred to as “ONS cause groups”.

ICD

International Classification of Diseases and Related Health Problems.

Infant

Under 1 year.

Inquest

Inquiry into the cause of an unexplained, sudden or violent death, held by a coroner.

Linkage

The matching of infant death records to their corresponding birth registration record.

Neonatal

Relating to infants aged under 28 days.

NS-SEC

National Statistics Socio-economic Classification categorises the socio-economic classification of people, and has replaced the Registrar General’s Social Class and the Socio-economic Group (SEG).

Occurrences

Number of deaths according to the date on which the death occurred.

ONS

Office for National Statistics.

Perinatal

Stillbirths and early neonatal.

Postneonatal

Relating to infants aged between 28 days and 1 year.

Registrar

Local Authority employee responsible for the registration of births, deaths, marriages and civil partnerships.

Registrations

Number of deaths according to the date on which the deaths were registered.

SOC 2010

Standard Occupational Classification 2010 is the current occupational classification. SOC 2010 codes, details of employment status and size of organisation are required for the derivation of NS-SEC. See NS-SEC.

Stillbirth

A child that has issued forth from its mother after the 24th week of pregnancy, and that did not at any time after being completely expelled from its mother breathe or show any signs of life.

Underlying cause of death

“The disease or injury which initiated the train of morbid events leading directly to death, or the circumstances of the accident or violence which produced the fatal injury” in accordance with the rules of the International Classification of Diseases (excludes deaths at age under 28 days).

VSOB

Vital Statistics Outputs Branch (at ONS).

WHO

World Health Organization.

Back to table of contents