Barry Caerphilly Growth (BCG) study

The Barry Caerphilly Growth study is the follow-up of an original randomized controlled trial involving pregnant mothers and their offspring, which continued until the age of 5 years. Pregnant mothers, between 1972 and 1974, were recruited through primary care from two towns in Barry and Caerphilly, in South Wales. They were randomized by an independent observer to either a ‘‘supplemented’’ or control group using random number tables. The supplemented group was provided with milk tokens throughout pregnancy and subsequently for their child (index case) until the age of 5 years, which entitled them to additional free milk delivered by their milkman. The primary outcome of the study was to test whether children who received additional milk were taller at 5 years than the control children but the results found no difference.

Around 20 years later, when the original participants were around 25 years of age, the participants were asked to attend a follow-up clinic where they completed questions on life style, had measures of anthropometry, lung function, arterial stiffness and blood taken for biochemical assays. This was done to test the developmental origins hypothesis that argues that foetal and post-natal growth and development can programme future risk of adult chronic disease risk factors.

Information security and privacy notice

The data we have collected on you for the BCG study is to enable us to look at how growth and development in the womb and over the first five years of life may be associated with risk factors for chronic diseases such as heart disease and diabetes. We have a wide range of different types of data; (a) questionnaire – either self-report or responses to an interviewer, (b) clinic measurements - things like weight or blood pressure, (c) biomarkers – measures derived from a blood sample such as cholesterol or genetic variations (e) outcome data such whether a participant is still alive and sadly if they have died what was the cause of death.

We take data security very seriously and adhere fully to the University of Bristol’s data protection and information security policies and procedures. University of Bristol is the Data Controller, and is responsible for ensuring that all data are securely stored, handled and used in accordance with the Data Protection Act 2018 and General Data Protection Regulation (GDPR). University of Bristol data policies and procedures comply with legislative and regulatory requirements, including NHS standards. The principal investigator remains the Data Custodian and oversees the way in which the study members’ data are looked after.

All contact information, such as names, addresses and telephone numbers of study members, is stored on an IT network that is protected by digital access controls, firewalls, security testing, full auditing, and other security provisions, to protect against the risk of unauthorised access. This system is also physically locked down and is only accessible by authorised personnel.

The same security measures are applied to all data that has been collected on study participants, be it questionnaire, clinical data or from any blood samples. All participants are coded with an arbitrary reference number, which means that researchers analysing results cannot directly identify participants and never see any contact information. Similarly, any data that is shared with research collaborators is fully anonymised to protect confidentiality and only used for approved ethical research purposes. All paper records are kept locked away in a secure storage area with restricted access. We will keep your data until we feel it no longer can add to our scientific knowledge and help society. At this moment this will review the value of the study again in 2025 at which point we will decide if we should continue to look after the data for longer or destroy it.

The legal basis for personal data to be obtained and processed for this purpose is Article 6 (1) (e) of the GDPR, which covers processing that is necessary for the performance of a task carried out in the public interest. The legal basis for processing information about particpants’ health is Article 9 (2) (i), which covers processing that is necessary for reasons of public interest in the area of public health, and Article 9 (2) (j) that covers processing that is necessary for reasons of public interest in the area of research.

Participants whose data is being processed have certain rights over their data. Further details can be found in the University of Bristol’s Data Protection Policy. Anyone who believes their data is being processed in a way that isn’t fully compliant with requirements has the right to submit a complaint to the Information Commissioner’s Office.

Any queries about the University of Bristol’s compliance with data protection requirements should be directed to or (0117) 3941824.

Edit this page