The terms used in relation to live births are defined as follows:
Live birth: 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 (ASRR): 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 years.
Live birth to mothers less than 15 years are included in the age 15 years category and are divided by the age 15 population. Similarly, live births to mothers aged greater than 49 years are included in the age 49 years 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.
Deaths are classified to the International Classification of Diseases, Version 10 (ICD10).
The Underlying Cause of Death (UCOD) has been defined by the World Health Organisation (W.H.O.) as
(a) the disease or injury which initiated the train of morbid events leading directly to death
or
(b) the circumstances of the accident or violence which produced the fatal injury.
From 1st January 2018, the CSO uses IRIS software to assign the UCOD. IRIS is a European developed automated coding software, endorsed by Eurostat and is maintained by the IRIS institute.
IRIS is an automatic system for coding multiple causes of death and for the selection of the underlying cause of death. It can be used in batch or interactively. The aim of IRIS is twofold:
To provide a system in which the language-dependent aspects are separated from the software itself. Moreover, the language-dependent parts are stored in database tables and can easily be modified.
To improve international comparability. IRIS is based on the international death certificate form provided by W.H.O. in Volume 2 of ICD-10 and the causes of death are coded according to the ICD-10 rules. Updates to ICD-10 are included according to the WHO-timelines.
Inquest deaths are coded manually due to the nature of the reporting of these cases. The difficulty lies in automatically assigning a verdict from a broad range of verdicts open to a Coroner or jury which include accidental death, misadventure, suicide, open verdict, natural causes (if so found at inquest) and in certain circumstances, unlawful killing.
Crude death rate (CDR): The number of deaths divided by the total population at that age (or age-group), multiplied by 1,000.
Standardised death rates: The (age) standardised death rate is a weighted average of age-specific mortality rates. The weighting factor is the age distribution of a standard reference population. The standardised suicide rate is calculated using the standard reference population, the European standard population as defined by Eurostat in 2012. The new European Standard Population (ESP) is the unweighted average of the individual populations of EU-28 plus EFTA countries in each 5-years age band (with the exception of under 5 and the highest age group of 95+). The ESP is calculated on the basis of the 2010-based population projections, averaged over the period 2011-30.
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.
