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:

• Information from childhood sweeps: Birth circumstances, birth weight, breastfeeding, general health, child development, specific conditions, disabilities/ special needs, hospital admissions, immunisation, medication, accidents, menstruation, eating problems, exercise, smoking, drinking, behavioural problems, emotional problems, sleeping problems, medical assessments (height, weight, audiometry, speech, co-ordination, vision, pubertal development), cognitive assessments, parental health, parental smoking.
• Information from adult sweeps: General health, specific conditions, disability/limitations, menopause, weight, accidents, mental health, well-being, sleep, smoking, alcohol, drug use, diet, exercise, cognition.
• 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

Steps

Since the birth survey there have been ten sweeps of the study at age 7 (1965), age 11 (1969), 16 (1974), 23 (1981) 33 (1991), 42 (2000), the biomedical survey at age 44 (2002), 46 (2004), 50 (2008) and 55 (2013).

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.

Object name

National Child Development Study – available at the UK Data Service.

Data type

Primary data

Ontologies

N/A

Format names and versions

SPSS, STATA

Creation dates

N/A

Dataset creators

• Centre for Longitudinal Studies: http://www.cls.ioe. ac.uk/
• Institute of Education: http://www.ioe.ac.uk/

Language

English

Programming language

N/A

Licence

UK Data Service End User Licence

Accessibility criteria

The majority of NCDS survey data can be accessed by bona fide researchers through the UK Data Service at the University of Essex. Anyone wishing to access the data will need to register with the UK Data Service before downloading. Some datasets are only available via Special Licence, or via the UK Data Service Secure Lab. Access arrangements comply with ESRC Research Data Policy.

Data from the biomedical sweep collected in 2002/3, including most data generated from the biological samples is available via Special License. However, access to the majority of genotypes generated from NCDS participants is governed by the Wellcome Case Control Consortium CDAC. Access to genotypes linked to other variables or applications for access to DNA and for new uses of biological samples is via the Access Committee for CLS Cohorts (ACCC).

Research metadata, including basic frequencies, is available using NESSTAR at the UK Data Service. The Centre for Longitudinal Studies (CLS) website provides copies of the questionnaires and documentation used in the study. The CLS data dictionary offers further metadata including variables and frequencies.

Repository location

DOI for each dataset at the UK Data Service is provided in 1.

Publication date

Publication date for each dataset at the UK Data Service is provided in Table 1.