National Child Development Study ( or 1958 Birth Cohort )

The National Child Development Study (NCDS) is one of Britain’s world-renowned national longitudinal birth cohort studies, three of which are run by the Centre for Longitudinal Studies at the Institute of Education, University of London. The study is an ongoing multi-disciplinary longitudinal study which follows the lives of around 17,000 people born in England, Scotland and Wales in a single week of 1958. Over the course of cohort members lives, the NCDS has collected information on health, physical, educational and social development, and economic circumstances among other factors. The broad aim of the study is to examine the impact that circumstances and experiences at one stage of life have on outcomes and achievements in later life. Since the birth survey in 1958, there have been ten ‘sweeps’ of all cohort members at ages 7, 11, 16, 23, 33, 42, 44/5 (a biomedical collection) 46, 50 and most recently at 55. Data has been collected from a number of different sources (the midwife present at birth, parents of the cohort members, teachers, doctors and the cohort members themselves). The data has been collected in a variety of ways including via paper and electronic questionnaires, clinical records, medical examinations, physical measurements, tests of ability and educational assessments. The information collected forms a high quality data resource for scientific investigations across a full range of domains of individuals’ lives and across different points in time in them. The study has been designed so as to ensure comparability with other major cohort studies so as permit the examination of links between social change and the changing experiences of different cohorts. The majority of NCDS survey data can be accessed by bona fide researchers through the UK Data Service at the University of Essex.


Introduction
NCDS began as the Perinatal Mortality Study (PMS) in 1958 and originally aimed to identify social and obstetric factors linked to stillbirth and neonatal death.The findings contributed to the improvement of maternity services in Britain and to a reduction in perinatal mortality.The PMS was not initially planned to be a longitudinal study but subsequently the National Children's Bureau was commissioned by the Central Advisory Council for Education (The Plowden Committee) to retrace the cohort at age 7 in order to monitor their educational, physical, and social development.Development through childhood was further examined at ages 11 and 16.
The age 23 survey tracked transitions into adulthood and information was gathered relating to employment and unemployment; post-school education; marriage, cohabitation and children; housing; income; health and health behaviours and leisure activities.Further adult sweeps at 33, 42, 46, 50 and 55 have focused on the formation and maintenance of adult identity across the following key domains: lifelong learning; relationships, parenting and housing; employment and income; health and health behaviour; citizenship and values.
A biomedical survey of the cohort (when they were aged 44-45 yr) was conducted, with several collaborating partners, under the Medical Research Council's 'Health of the Public' initiative.The primary objective was to examine how developmental, lifestyle, and environmental factors act throughout the lifespan to influence ill health, and physiological and psychological function in early middle age.
Health information collected by the study is summarised below:

Temporal coverage
NCDS began as the Perinatal Mortality Study (PMS), in 1958.NCDS has followed participants throughout childhood into adulthood and aims to continue to track their lives right through to the end.
The birth survey involved the use of questionnaires completed by the midwife present at the birth of the study members.In addition, information was extracted from clinical records.
At ages 7, 11 and 16 parents of the children in the study were interviewed by health visitors.Information was also gathered from schools via the child's class teacher and head teacher and from the children themselves via means of questionnaires and assessments.
Adult sweeps from 23 onwards have typically involved face-to-face visits to study members which have been conducted by interviewers working for research companies on behalf of the organisation responsible for running the study.From age 30 onwards most information has been collected using computer aided interviews.Information was gathered from partners and children for a third of the sample at age 33.The biomedical study at age 44 was conducted via nurses.The age 46 follow-up was conducted via telephone and the age 55 follow-up used a sequential mixed mode approach where study members were first invited to participate online and non-respondents were then contacted via telephone.
More information about each follow-up is provided on the Centre for Longitudinal Studies (CLS) website.

Sampling strategy
The NCDS original target sample was all births in England, Scotland and Wales in one week of March 1958.In addition, in advance of the age 7, age 11 and age 16 follow-ups the sample was augmented with immigrants born within the relevant week.

Quality control
Since 2000 the majority of the data has been collected via Computer Aided Interviewing (CAI) which allows the complex routing of the questionnaire instruments to be automatically controlled.Consistency checks are built into the CAI program to minimise the potential for erroneous data entry.The CAI instruments are rigorously checked prior to fieldwork.Pilot studies are conducted prior to commencement of the main stage of data collection in order to fully test the data collection instruments and all fieldwork procedures.

Privacy
Study members have been guaranteed anonymity.Identifiable data is not included in the datasets made available for research.Researchers accessing the data via the UK Data Service must abide by the terms of an End User Licence which forbids any attempt to identify an individual.Datasets judged to have a greater disclosure risk are made available via Special Licence which involve additional access conditions.

Ethics
Over the years, those responsible for the study have been concerned that appropriate procedures for ethical review and consent are followed but the approach has changed significantly.Currently in the UK, probably the most important route for ethical approval for studies like NCDS is the National Health Service (NHS) Research Ethics Committee (REC) system.NHS Research Ethics Committees (RECs) are appointed by the Strategic Health Authorities in England, their equivalents in Scotland and Wales and the Health and Social Care Business Services Organisation in Northern Ireland.RECs safeguard the rights, safety, dignity and well-being of people participating in research.They review applications for research and give an opinion about the proposed participant involvement and whether the research is ethical.REC ethical approval has been sought for NCDS follow-ups from 2000 on.Earlier sweeps pre-dated the establishment of the MREC system.Available records suggest that there was only internal ethical review for these surveys.

• Information from childhood sweeps: Birth
• Information from the biomedical survey: Near, distance and stereo vision; hearing; lung function; blood pressure and pulse, height and weight; and waist and hip circumference.Samples of blood were taken from which DNA was extracted and immortalised cell cultures created (where consent was provided), from which the cohort has been extensively genotyped.Blood samples also used to measure lipids, clotting factors, inflammatory markers, total specific serum IgE.Saliva was collected to measure levels of cortisol.Context Spatial coverageDescription: The National Child Development Study (NCDS) follows the lives of around 17,000 people born in England, Scotland and Wales in a single week of 1958.

Object name
National Child Development Study -available at the UK Data Service.Dataset creators• Centre for Longitudinal Studies: http://www.cls.ioe.ac.uk/ • Institute of Education: http://www.ioe.ac.uk/

Table 1 :
Datasets at the UK Data Service.