Technical notes:
Live Births:
The terms used in relation to live births are defined as follows:
A live birth is defined as the complete expulsion or extraction from its mother of a product of conception, irrespective of the duration of pregnancy, which, after such separation, breathes or shows any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the placenta is attached
Parity: Parity is the number of previous live born children to a woman.
Birth Order: Birth order is the number of live born children a woman has in the order in which they are born.
Parity and Birth order: A first birth relates to parity 0 or birth order 1 i.e. birth order = parity + 1.
Crude birth rate (CBR): The number of live births divided by the total population at that age (or age-group), multiplied by 1,000.
Age specific fertility rate (ASFR): The number of live births at a certain age (or age-group) divided by the female population at that age (or age-group) multiplied by 1,000.
Total period fertility rate (TPFR): The sum of the ASFRs, divided by 1,000 i.e. the expected number of children a woman will have in her lifetime based on the fertility of that year.
Age specific reproduction rate (ASFR): The number of female live births at a certain age (or age-group) divided by the female population at that age (or age-group), multiplied by 1,000.
Gross reproduction rate (GRR): The sum of the ASRRs divided by 1,000 i.e. the expected number of daughters a woman will have in her lifetime based on the fertility of that year.
Net reproduction rate (NRR): The sum of the products of the ASRR's and the expected number of female years to be lived at that age, divided by 1,000 i.e. the GRR adjusted for female mortality.
The difference between the gross and the net reproduction rates is an indicator of female mortality.
Average age at maternity: The sum of the products of the ages at maternity of live births and their ages divided by the number of live births.
Average age at maternity of first birth: The sum of the products of the ages at maternity of first live births and their ages divided by the number of first live births.
Childbearing years are regarded as between 15 and 49.
Live birth to mothers less than 15 are included in the age 15 category and are divided by the age 15 population. Similarly, live births to mothers aged greater than 49 are included in the age 49 category and are divided by the age 49 population.
Average of mean ages: Live births where the age at maternity is not stated are excluded from the calculation.
Technical Notes:
Deaths
International classification of Diseases, Injuries and Causes of Death (ICD-10)
The Tenth Revision of the International classification of Diseases, Injuries and Causes of Death (ICD-10), as recommended by the World Health Organisation, has been used to classify deaths in Ireland for the 2012 data. It replaces the Ninth Revision, which was used from 1979 to 2006.
Automated coding software produced by the National Centre for Health Statistics (NCHS) in the US is used in coding the underlying causes of death for Irish data, supplemented by manual coding in certain cases.
The main changes to the classification of diseases between ICD-9 and ICD-10 are as follows:
- ICD-10 has over 3,000 more codes than ICD-9
- Inclusion of additional underlying causes (eg AIDS/HIV, chromosomal abnormalities)
- Expansion of certain underlying causes existent in ICD-9, for certain diseases, providing for the recording of greater levels of detail (e.g. acute myocardial infarction, perinatal conditions, viral hepatitis)
- Movement of underlying causes of death between ICD chapters (e.g. haemorrhage moved from the circulatory chapter to the symptoms and signs chapter in ICD-10, certain disorders of the immune mechanism moved from the endocrine chapter to the blood chapter in ICD-10 and certain disorders of blood moved from the blood chapter to the neoplasm chapter in ICD-10)
- Contraction of certain underlying causes of death (e.g. autoimmune disease and connective tissue disease are given the same code in ICD-10)
- Changes in the inclusion and exclusion guidelines for certain underlying causes of death
- Re-ordering of certain chapters and underlying causes
- Alphanumeric codes used instead of numeric codes
Additionally, there have been changes to the selection rules applied to determine the underlying cause of death. The most significant change relates to Rule 3 which allows a condition from Part I or Part II of the death certificate to be selected as the primary condition if it is an obvious direct consequence of another reported condition. There are a number of guidelines presented for this rule, most significantly the guideline in relation to pneumonia. The effect of this rule change reduces the number of deaths assigned to pneumonia and alternatively assigns the underlying cause of death to the chronic debilitating disease.
Certain official updates to ICD-10 are also incorporated in the coding of the cause of death. In particular, mental and behavioural disorders due to psychoactive substance use (F10-F19), with mention of intestinal infectious diseases (A00-A09), accidental, intentional self and undetermined intent poisoning by and exposure to noxious substances (X40-X49, X60-X69, Y10-Y19) or assault by chemical or noxious substance (X85-X90), are now coded to the latter.
http://www.who.int/classifications/icd/OfficialWHOUpdatesCombined1996-2008VOLUME2.pdf
For further information on the difference listed above and additional changes and differences between ICD-9 and ICD-10, please go to http://www.who.int/classifications/help/icdfaq/en/index.html
These changes have the effect of data being coded to different underlying causes of death at the most detailed level of ICD-10 and at the higher chapter level of ICD-10. For this reason, data cannot be easily compared across ICD-9 and ICD-10.
Technical notes:
Stillbirths, Infant Mortality and Maternal Mortality
The terms used in relation to stillbirths and infant mortality are defined as follows:
Stillbirth: Stillbirth weighing 500 grams or more or at gestational age of 24 weeks or more. this definition applies to stillbirth figures from 1995 onwards.
Late foetal death: Foetal death at or over 28 weeks gestation. this definition was applied up to 1994 inclusive.
Early neonatal death: Death at ages under 1 week live born infant.
Perinatal deaths: Stillbirths or late foetal deaths plus early neonatal deaths.
Late neonatal deaths: Death between the ages of 1 week and 4 weeks of live born infant.
Neonatal death: Death at ages under 4 weeks of live born infant.
Post neonatal death: Death between the ages of 4 weeks and 1 year of live born infant.
Infant death: Death at ages under 1 year of live born infant.
Maternal death: a maternal death is the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and the site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes.
Stillbirth rate: Stillbirths divided by total live births plus stillbirths, multiplied by 1,000.
Late foetal mortality rate: Late foetal deaths divided by total live births plus late foetal deaths, multiplied by 1,000.
Early neonatal mortality rate: Early neonatal deaths divided by total live births, multiplied by 1,000.
Perinatal mortality rate: Perinatal deaths divided by total live births plus stillbirths, multiplied by 1,000.
Late neonatal mortality rate: Late neonatal deaths divided by total live births, multiplied by 1,000.
Neonatal mortality rate: Neonatal deaths divided by total live births, multiplied by 1,000.
Post neonatal mortality rate: Post neonatal deaths divided by total live births, multiplied by 1,000.
Infant mortality rate: Infant deaths divided by total live births, multiplied by 1,000.
Maternal death rate: Maternal deaths divided by total live and stillbirths multiplied by 100,000.
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