The eLIXIR (early LIFe data Cross-Linkage in Research) Cohort.

The foundations of health are established at the very earliest stages of life. If the developing embryo, fetus, newborn baby and young child are given the best possible start in life, this will provide protection against poor health when they are adults. To achieve these best beginnings, we have to understand what can go wrong at each of those key stages in early life.

Some causes are more obvious than others; for example, being born prematurely can lead to breathing problems, but there are many other factors that can interact in a complex way to affect the child's mental and physical health for life. If we know what these factors are, we can work to prevent them or their harmful effects.

The eLIXIR study aims to establish a novel way of unravelling the complexity of harmful early life influences, using routine information from mothers' and babies' health records. Whilst a few people choose to opt-out of providing their records, the vast majority support our strategy. It has the advantage of including almost everyone in our maternity population, so that all ethnic and social groups are represented.

Having shown that we can link together mothers and babies' mental and physical health records from GP practices and hospitals, we are now ready to invite researchers from around the UK to use our data, and explore the early life influences that affect children's health and find ways of preventing disease in adulthood. eLIXIR started in 2018, and we already have data from more than 40,000 pregnant women and their children, and we will continue collecting mums' data until we have data from 100,000 pregnancies; this will take about 4-years. This very large study of mums and babies gives researchers the opportunity to undertake novel approaches to learning from the data, all within an electronic, trusted research space that protects the identify of the mums and babies at all times.

The people providing our data live in South East London, where mental and physical health problems are common. The mothers come from many different ethnic groups and are often socially and economically deprived. Therefore, by working in this community, eLIXIR concentrates on those who most need help, and its findings should be relevant to other disadvantaged communities across the UK.

Indeed, we will test this out by working with other groups, in Wales, Scotland and North East England, who are also using routine health data to study mothers and their babies, and the future health of the children.

Another important element of the study is the collection of blood samples. We do not obtain these from all mothers and babies - just those who give permission to do so when they come to clinics in early pregnancy. We already have samples from more than 1400 participants who are similar in their characteristics to our population of mums.

This store of blood samples is important, because there are many different kinds of measurements that can be done on them, to add to the information that we have from the GP and hospital health records.

Our plans will be realised by recognition as an MRC 'Longitudinal Population Study'. This would provide us with funding support for the eLIXIR infrastructure, primarily to fund staff who collect mums' and babies' information from different sources, link that information together in the trusted, safe space, or collect the samples. In the future, we plan for eLIXIR to become self-sufficient, as researchers from all over the UK access the information and samples, and contribute to these costs.