Conception statistics are produced by the Office for National Statistics (ONS). National Statistics are produced to high professional standards set out in the Code of Practice for Official Statistics. They undergo regular quality assurance reviews to ensure that they meet customer needs. They are produced free from any political influence.
Conception statistics are estimates. Conceptions include maternities (the number of pregnant women who give birth) and abortions. This information is obtained from administrative sources: abortion notifications and birth registrations. Conception statistics do not include miscarriages, or illegal abortions.
To meet user needs, timely but provisional Quarterly conceptions to women aged under 18 are published by area of usual residence (down to counties, unitary authorities and metropolitan county districts) in England and Wales. Quarterly conception rates and rolling annual rates are also provided where area of usual residence is within England.
The annual Conception statistics publication consists of a number of data tables accompanied by a statistical bulletin. The tables released show the latest year’s figures with some tables also showing historical data for comparison.
The Quality and Methodology Information document for conception statistics provides overview notes which pull together key qualitative information on the various dimensions of quality as well as providing a summary of methods used to compile the output.
Following the review of conception outputs in 2011, Annual Conception Statistics are released in February or March (around 14 months after the end of the data year). Prior to 2009, annual data were released twice a year: a provisional annual release in February or March and a final annual data release in the Annual Reference Volume Conception statistics, published in the autumn. By moving to 1 annual release a year the cost of producing conception statistics has been reduced without a significant impact on data quality.
Prior to the 2005 data year (published in 2007), conception statistics were released as a supplement to Birth Statistics (Series FM1), rather than in a standalone volume.
Annual Abortion Statistics are published by the Department of Health (DH) by: age of woman; number of previous abortions; length of gestation; source of funding; health area of usual residence of woman; method of abortion; ethnicity of woman and grounds for abortion.Back to table of contents
Conception figures are covered by the disclosure control protocol for abortion statistics. In June 2015 this protocol was revised. The requirement to suppress counts and rates is determined by the number of women in the underlying population. Full details can be found in the Disclosure control protocol for abortion statistics. Occasionally it is necessary to apply secondary suppression to avoid the possibility of disclosure by differencing.
Prior to June 2015, for conceptions leading to abortions, counts less than 10 and rates based on fewer than 10 events were suppressed. To protect the confidentiality of conceptions data, all counts lower than 5, and all rates based on fewer than 5 events were also suppressed.
Figures in some tables may not add precisely due to rounding.Back to table of contents
The existing provisions for the registration of births and the processing, reporting and analysis of births data appear in different legislation that reflects the distinct and separate roles of the Registrar General for England and Wales and the UK Statistics Authority. The Registrar General is guided by the following:
- Births and Deaths Registration Act 1953, which covers all aspects of the registration of births and stillbirths.
- Population (Statistics) Act 1938, which deals with the statistical information collected at registration.
- Population (Statistics) Act 1960, which makes further provision for collecting statistical detail at registration.
- Registration of Births, Deaths and Marriages Regulations 1968, which added questions on father’s and mother’s place of birth to the details requested at registration.
- Still-Birth (Definition) Act 1992, which altered the definition of a stillbirth to 24 or more weeks completed gestation, instead of the previous definition of 28 or more weeks completed gestation.
- National Health Service Act 2006 and National Health Service (Wales) Act 2006 which consolidate legislation relating to the Health Service and separate provision of the health service in Wales from that in England. The Acts require notification of a birth to the relevant body or bodies where the birth occurred as may be determined in accordance with regulations. Both Acts include provisions both for the supply of information about birth notifications by the National Health Service (NHS) and the supply of information on individual registered births by the Registrar General to the NHS.
- Human Fertilisation and Embryology Act 2008, which gave provision for same sex female couples to jointly register the birth of a child as mother and parent. It also allows for two men to obtain a parental order through the courts to be officially registered as the parents of a child post-registration
The UK Statistics Authority is guided by the following:
- Registration Service Act 1953, as amended by the Statistics and Registration Services Act 2007, which in section 19 requires the UK Statistics Authority to provide annual abstracts of live births and stillbirths
- Abortion Act 1967, which permits termination of pregnancy by a registered practitioner, subject to certain conditions and the Abortion Regulations 1991, that enables the Chief Medical Officers to supply information about abortions to the UK Statistics Authority
- Human Fertilisation and Embryology Act 1990, Section 37 made changes to the Abortion Act 1967
- Statistics and Registration Service Act 2007, which created the Statistics Board, now known as the UK Statistics Authority, and defined its functions and powers
Conception statistics bring together records of birth registrations collected under the Births and Deaths Registration Act 1953 and of abortion notifications supplied under the Abortion Act 1967. They include all the pregnancies of women resident in England and Wales which lead to one of the following outcomes:
- a maternity at which 1 or more live births or stillbirths occur, which is registered in England and Wales
- a termination of a pregnancy by abortion under the 1967 Act, which takes place in England and Wales. Pregnancies which lead to spontaneous abortions (that is, miscarriages) are not included.
Maternities which result in 1 or more live births or stillbirths are counted once only.
4.1 Maternities data
The registration of life events (births, deaths, marriages and civil partnerships) is a service carried out by the Local Registration Service in partnership with the General Register Office (GRO). Most of the information, for both live births and stillbirths, is supplied to registrars by 1 or both of the parents.
For stillbirths, details of cause of death, duration of pregnancy (gestation) and weight of foetus are supplied on a certificate or notification by the doctor or midwife either present at the birth, or who examined the body. The certificate or notification is then taken by the informant to a registrar.
For all births the mother’s usual address is entered. This information is used for tables showing usual residence of mother. Informants are also required to provide further information, treated as confidential, under the provisions of the Population (Statistics) Acts. The items relevant to this publication are listed:
- the mother’s date of birth
- the date of the parents’ marriage or civil partnership, if the child’s parents were married or in a civil partnership with each other at the time of birth
When we receive birth registrations, a number of checks are carried out on records to ensure that they are valid. Checks are more frequent on those records with extreme values for main variables (such as age of mother) as these have a greater impact on published tables. For example, when looking at multiple births, checks are carried out to ensure that the number of triplets is divisible by 3 and that there is 1 maternity recorded for each set of triplets. Any birth records which appear questionable are raised with GRO on a monthly basis for further investigation.
4.2 Abortions data
Information on abortions is derived from notifications supplied under the Abortion Act 1967. These are sent by registered practitioners to the Chief Medical Officer of the Department of Health, or to the Chief Medical Officer of the Welsh government. The details supplied include the woman’s date of birth, marital status and usual residence.
Abortion notifications go through an agreed series of checks and values for missing items are imputed at DH before being supplied to us, this ensures data are of sufficient quality. Each quarter there are also updates on previous quarters which have not been previously finalised; these updates will contain records where DH raised queries which have been resolved.Back to table of contents
Conception statistics do not include miscarriages or illegal abortions. NHS Choices estimate that 1 in 5 confirmed pregnancies will end in miscarriage. It is impossible to determine the extent of illegal abortions, for example, by women using drugs bought from the Internet. The only statistics available are where complications arise from illegal abortions resulting in illness or death. In 1965, before abortion was legalised, the number of women discharged from hospital with post-abortion sepsis (Col 202) was 3,050; in 1982 it was 390. Why Mothers Die 2000-2002: The Sixth Report of the Confidential Enquiries into Maternal Deaths in the UK found that in the 3 years from 1961 to 1963, 139 women were recorded as dying as a result of abortions. Saving Mothers’ Lives: reviewing maternal deaths to make motherhood safer 2006-2008 reported no deaths from abortions from 2006 to 2008. Given the steady rise in numbers of legal abortions since 1968, and the improvements in access to abortion it can be assumed that the vast majority of abortions carried out in England and Wales today are legal ones.
During 2013 the number of Ground E HSA4 notifications (“substantial risk” that the child might be born “seriously handicapped”) was found to be lower than the number reported to the congenital anomaly registries. DH has worked closely with the National Down’s Syndrome Cytogenetic Register (NDSCR) to explore this discrepancy and make recommendations. Results suggested that an abortion notification was made for about 54% of NDSCR records. Hence there is potentially an undercount of Ground E abortions. DH continues to work closely with the Royal College of Obstetricians and Gynaecologists (RCOG) and other organisations in implementing the recommendations where possible.
To enable the publication of conception statistics the date of conception and the woman’s age at conception need to be estimated. The estimation methods used are detailed later in this document.
Other issues which have affected the quality of conception statistics in the past are detailed below.
5.1 Registration Online (RON)
In November 2006 a pilot for a web-based Registration Online system for births and deaths (RON), commenced in 5 registration districts. This enabled registrars to record births, stillbirths and deaths online. Following the success of this pilot, RON was implemented in most register offices on 26 March 2007. However, as a result of significant performance problems, the system was suspended on 10 April 2007 resulting in around half of registrars reverting back to using the previous electronic system, Registration Service Software (RSS).
From 8 May 2007, almost all register offices were submitting data electronically using either RON or RSS. Any remaining birth registrations that were held only on paper at register offices were later entered onto the RON system at ONS, or by the local registration service. Once all the birth records were available electronically, we completed a rigorous statistical quality assurance process.
Work to improve the performance of RON continued throughout 2008. During this time a further 15 registration districts moved back onto RON. By the end of 2008, 56% of registration districts were using RON for birth and death registrations.
The RON system was fully rolled out on 1 July 2009 with all register offices using it to record births from this date. With the introduction of RON, it has become possible to carry out some additional validation checks at the point of registration, such as, validation of address and postcode.
5.2 Maternities data
Maternities data included in our conception statistics have been derived from the births database. Where the mother’s date of birth was not stated at registration it is obtained from the corresponding birth notification record. Where this is not possible, the age of mother is imputed. More information on the imputation method can be found in section 1.3 of the User guide to birth statistics.
Conception statistics for 2009 by age exclude maternities where the mother’s age was not recorded and the birth occurred in 2010. For the 2009 data year, final conception statistics were released before the 2010 annual births dataset had age of mother imputed using the most appropriate donor record from the entire annual dataset.
From 2010 conceptions data onwards, where a missing age of mother cannot be obtained from the corresponding birth notification, age of mother is imputed using the most recently processed complete record of similar characteristics to the incomplete record. The impact on conception statistics is negligible since the percentage of records where age of mother remains missing following birth notification matching is very small. No statistical bias is introduced as the records missing age of mother are distributed across all areas of England and Wales. The impact on the comparability of statistics over time and between areas is negligible.
|Year of conception||Records with mother’s date of birth not stated at registration|
|Percentage||Percentage still missing following birth notification matching|
|Source: Office for National Statistics|
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RON system issues were encountered in November 2014. As a consequence births had to be manually registered for over a week and these were keyed onto RON when the issues had been resolved. This resulted in a higher than usual level of records where the mother’s date of birth was missing. Birth registrations in November 2014 related to conceptions in both 2013 and 2014.
5.3 Abortions data
Under arrangements made following implementation of the Abortion Act 1967, the Office for National Statistics and its predecessors processed and analysed the abortion notification forms (HSA4) sent to the Chief Medical Officers of England and Wales. From 1 April 2002, responsibility was transferred to the Department of Health where a new system was introduced to process the new abortion notification forms that were made available from 18 April 2002. The collection of marital status information was affected in the changeover between the old and the new abortion notification form. There were some discontinuities in the recording and coding of marital status in the 2002 abortions data following the introduction of the new form. For further details see section 1.3 of Conception statistics 2002.
5.4 Further information on the quality of conception statistics
Checks on conceptions data are performed before the annual data extract is taken. These comprise frequency checks for age, missing ages, imputed ages, and quarter of conception. Further examinations are carried out once the data extract has been taken. They include checks similar to those done before extraction and a further set of checks to ensure that the frequency distributions for both maternities and abortions by age and area of residence are both valid and plausible and broadly similar to those for the previous year’s data.
Once tables for publication have been produced the following checks are conducted:
- systematic checks of totals (row, column, and other) against known correct figures
- checks of individual cells against correct figures
- checking figures are consistent and plausible, that is, that they are what would be expected compared to the previous year’s tables
The Quality and Methodology Information document for conception statistics provides overview notes which pull together key qualitative information on the various dimensions of quality as well as providing a summary of methods used to compile the output.Back to table of contents
6.1 Base populations
The population estimates which are used to calculate conception rates are mid-year estimates of the resident population of England and Wales based on the Census of Population. Our mid-year population estimates are updated figures using the most recent Census, allowing for births, deaths, net migration and ageing of the population.
The population estimates used are the most up-to-date when rates are produced. The specific population estimates used to calculate rates are detailed alongside published tables. Sometimes it is necessary to revise conception rates following population estimate revisions. Any revisions to conception rates are footnoted on tables.
The quarterly populations used in rate calculations are adjusted using mid-year population estimates or a combination of mid-year population estimates and population projections to estimate what the likely population would have been for the mid-quarter.
The rolling annual rates are calculated using the last 4 quarters' conception numbers and the populations used are mid-year population estimates from the corresponding years weighted accordingly.
Further information on population estimates, and their methodology, can be found on our website.
6.2 Areal coverage
Conception figures include only live births, stillbirths and abortions that occurred in England and Wales to women usually resident in England and Wales.
Numbers and rates of conceptions are given by the woman’s area of usual residence based on boundaries in place when the area derivation was conducted (for example, 2015 conceptions used boundaries in place in January 2017). The postcode of the woman’s address at the time of the maternity or abortion is used to assign the area of usual residence at the time of the conception.
Until the 2009 data year for conceptions, we assigned “area of usual residence” using a look-up product (the National Statistics Postcode Directory). This product associated postcodes with a number of geographical levels (for example, local authority, region). The postcode was allocated to each level of geography using a point-in-polygon methodology. Although this method is spatially accurate, it does not provide the stable building blocks needed for comparing geographies at different levels.
From the 2010 data year for conceptions, we have assigned “area of usual residence” by first linking each postcode to an output area using this same point-in-polygon methodology, and then linking to all higher geographies by using a population weighted, best-fit look-up to output area. This means that postcodes are allocated to a higher geography based on where the output area population weighted centroid lies. This is in line with the Geography Policy for National Statistics.
Switching to the new area allocation method has negligible impact on conception statistics down to local authority level. However, the new method improves comparability of conception statistics for sub-national areas over time.
For more information about these methods, see National Statistics Postcode Products and Assigning Life Events data to sub-national areas: an assessment of a change to the methodology.
6.3 Estimating the date of conception
Information on the exact date of conception cannot be obtained from the registration details for either births or abortions. Date of conception is estimated by subtracting the gestation period from the baby’s date of birth or the date of termination.
Maternities (1 or more live births)
Conception is assumed to occur 14 days (2 weeks) after the start of the last menstrual period and the time between the last menstrual period and birth is assumed as 40 weeks (referred to as gestational age). Therefore the length of pregnancy from conception to birth is assumed to be 38 weeks (40 weeks minus 2 weeks) for all maternities with 1 or more live births.
Maternities (all stillbirths)
Gestational age is recorded at the registration of a stillbirth. The date of conception is estimated as date of birth minus stated gestational age plus two weeks to allow for time to conceive.
For example, if a gestational age is 30 weeks and the date of birth is 10 October, then date of conception is:
(10 October - 30 weeks) + 2 weeks = 28 March
On the few records where gestational age is not recorded or available at registration, the length of pregnancy from conception to stillbirth is assumed to be 33 weeks.
For conceptions in 1980 and earlier years, the date of conception is taken as the date of the start of the last menstrual period, plus 2 weeks. For conceptions in 1981 and subsequent years, gestational age has been collected on all notifications of abortions. The date of conception for abortions is therefore estimated as the date of termination less the stated gestational age plus 2 weeks to allow for conception.
For example, if a gestational age is 10 weeks and date of termination is 10 October, then date of conception is:
(10 October - 10 weeks) + 2 weeks = 15 August
6.4 Estimating a woman’s age at conception
A woman’s age at conception is estimated from her date of birth, as stated on the birth registration or abortion notification, together with the estimated date of conception. Where the mother’s date of birth is not stated at registration we obtain it from the corresponding birth notification record. Where this is not possible and the age of mother is imputed (for more information on imputation see section 1.4). In the small number of cases of abortions where the woman’s date of birth was not recorded, the case is not used for statistical analysis.
The woman’s age at conception is calculated as the interval in complete years between her date of birth and the date she conceived (estimated as described in section 2.3 above). However, where conception occurs in the same calendar month as the woman’s birthday, this can result in the estimated age of mother at conception being either a year too low – if the baby is born live after less than 38 weeks – or a year too high – if the baby is born live at over 38 weeks. The method for estimating a woman’s age at conception in such cases was revised in 1999 to take into account the mother’s day of birth and day of conception in addition to the month and year as used previously. This resulted in a revision to figures published before 1999. A full explanation can be found in Birth statistics 1998.
6.5 Conceptions within and outside marriage or civil partnership
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. Abortion notifications also contain information about whether the woman was in a civil partnership.
A birth within marriage or civil partnership is that of a child born to parents who were lawfully married or in a civil partnership with each other either:
- at the date of the child’s birth
- 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. Conceptions outside marriage or civil partnership which lead to maternities within marriage or civil partnership are restricted here to those where the birth occurred within 8 months (35 weeks) of marriage or civil partnership. However, the date of conception and age of woman at conception are estimated from a date 38 weeks before birth, as in the case of all other conceptions leading to live births.
For abortions coded on the old form HSA4 originating from ONS, the categories of marital status were:
- (a) single
- (b) married
- (c) widowed
- (d) divorced
- (e) separated
For abortions coded on the new form HSA4 originating from Department of Health, marital status was reclassified as:
- (a) single no partner
- (b) married
- (c) single with partner
- (d) single not known
- (e) divorced
- (f) widowed
- (g) separated
- (h) civil partnered
To calculate rates separated mothers are included with married mothers because there are no official population estimates for the “separated” marital status category.
Due to the relatively small numbers of conceptions to same sex couples, conceptions to same sex couples who are married or in a civil partnership are included with conceptions within marriage, while conceptions to same sex couples not in a marriage or civil partnership are included with conceptions outside marriage. The number of conceptions to same sex couples is footnoted on relevant tables to assist users. Given the relatively small numbers of conceptions to same sex couples the impact on statistics is negligible.Back to table of contents
Special extracts and tabulations of conceptions data for England and Wales are available to order (subject to legal frameworks, disclosure control, resources and our charging policy, where appropriate). Enquiries should be made to Vital Statistics Outputs Branch (firstname.lastname@example.org or telephone: +44 (0)1329 444110). User requested data will be published onto our website.
We welcome feedback from users on the content, format and relevance of this release. Please send feedback to the email address aboveBack to table of contents
Area Based Analysis, Conceptions Deprivation Analysis Toolkit, 2009–11 and Area Based Analysis, Conceptions and Deprivation Analysis, England and Wales, 2008-10 are available on our website. These interactive Excel toolkits allow people to explore under 18 and under 16 conceptions statistics for 2009 to 2011 and 2008 to 2010 and how these link to various measures of deprivation at the national, regional and local level. A short story was published alongside each toolkit taking a closer look at the link between under 18 conceptions and unemployment.Back to table of contents
Conception statistics in Scotland are available for women aged under 16, under 18 and under 20. They have been produced to a revised methodology since 2007 to become more comparable to those in England and Wales. Prior to this, they included therapeutic miscarriages which required a hospital stay and were based on financial years rather than calendar years. More information on the differences in methodology which existed previously can be found on the ISD Scotland website.
In Northern Ireland it is lawful to perform an operation for the termination of a pregnancy, where:
- it is necessary to preserve the life of the woman
- there is a risk of real and serious adverse effect on her physical or mental health, which is either long-term or permanent
In any other circumstance it would be unlawful to perform such an operation. Due to the small numbers of abortions carried out in Northern Ireland each year, and in order to protect patient confidentiality, information on terminations of pregnancy is only released at Northern Ireland and Health and Social Care (HSC) Trust level. Further information on the number of terminations of pregnancy carried out in Northern Ireland can be found on the Northern Ireland Department of Health's website.Back to table of contents
Statistical bulletins providing supporting commentary for the annual release of conception statistics from 2011 onwards are available on our website.
Between 1999 and 2011, annual reports on conceptions in England and Wales were linked into Health Statistics Quarterly.
Prior to 1999 we published annual reports summarising patterns and trends, in Birth Statistics (Series FM1), for conceptions and live births. These contained basic information on annual conceptions and birth statistics, and were issued soon after the data became available.
Some other background publications on conceptions are listed below. Most are from the journals Population Trends and Health Statistics Quarterly, and where not available on the National Statistics website may be obtained from us.
Babb, P. (1993). ‘Teenage conceptions and fertility in England and Wales, 1971–91’. Population Trends 74, pp 12–17.
Botting, B. and Dunnell, K. (2000). ‘Trends in fertility and contraception in the last quarter of the 20th century’. Population Trends 100, pp 32–40.
Dattani, N. and Chow, Y.H. (2009). ‘Estimating conception statistics using gestational age information from NHS Numbers for Babies data’. Health Statistics Quarterly 41, pp 21–27.
Dattani, N. Sheers, D. and Uren, Z. (2007). ‘Teenage conceptions by small area deprivation in England and Wales, 2001–2002’. Health Statistics Quarterly 33, pp 34–39.
Griffiths, C. and Kirby, L. (2000). ‘Geographic variations in conceptions to women aged under 18 in Great Britain during the 1990s’. Population Trends 102, pp 13–23.
Lancucki, L. and Ruddock, V. (2001). 'The calculation of abortion rates for England and Wales'. Health Statistics Quarterly 10, pp 25–32.
Wood, R. (1996). ‘Subnational variations in conceptions’. Population Trends 84, pp 21–27.
Wood, R. Botting, B. and Dunnell, K. (1997). ‘Trends in conceptions before and after the 1995 pill scare’. Population Trends 89, pp 5–12.Back to table of contents
The legal termination of a pregnancy under the 1967 Abortion Act.
Civil partnerships are a legal confirmation of a relationship between two people of the same sex.
Code of Practice for Official Statistics
The principles and protocols followed and upheld by all those involved in producing National Statistics.
ONS uses the definition – a pregnancy of a woman which leads either to a maternity or an abortion.
A dissolution is a legal end to a civil partnership obtained through the courts.
General Register Office (GRO)
The GRO (part of Her Majesty’s Passport Office) is responsible for ensuring the registration of all births, deaths, marriages and civil partnerships that have occurred in England and Wales and for maintaining a central archive.
The duration of pregnancy from conception.
The person(s), normally 1 or both parents, who provide the registrar with the information required at the registration of a birth.
A birth outside marriage registered by both the mother and father of the child. Both parents’ details are recorded and both must be present at the registration.
A baby showing signs of life at birth.
A pregnancy resulting in the birth of 1 or more live-born or stillborn children. The number of maternities represents the number of women giving birth rather than the number of babies born (live-born and stillborn).
A document completed by the doctor or midwife present at the birth. The notification provides certain data items, such as the birthweight, to the birth record.
Office for National Statistics. We are the executive office of the UK Statistics Authority.
Population (Statistics) Act
These Acts makes provision for certain information to be collected at the registration of the birth for statistical use. This information is confidential and is not entered on the register.
Local authority employee responsible for the registration of births, deaths, marriages and civil partnerships.
Statutory appointment with responsibility for the administration of the registration acts in England and Wales and other related functions as specified by the relevant legislation.
Generic term for registrar, superintendent registrar and additional registrars.
Registration Online. A web-based system which enables registrars to record births, stillbirths, deaths and civil partnerships online.
Only birth born in a maternity.
A birth outside of marriage registered only by the mother. No information on the father is recorded.
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.
UK Statistics Authority
The UK Statistics Authority is an independent body operating at arm's length from government as a non-ministerial department, directly accountable to Parliament. It was established on 1 April 2008 by the Statistics and Registration Service Act 2007.
Vital Statistics Outputs Branch (at ONS).Back to table of contents