'The greatest loss': Sarah Brown on heart-breaking death of baby daughter with husband Gordon Brown

Jennifer died in January 2002, ten days after she was born at 33 weeks, seven weeks premature.

Mrs Brown and her husband, former prime minister Gordon Brown, set up the Jennifer Brown Research Laboratory in 2004.

The laboratory, at the University of Edinburgh, is working to improve understanding of what causes early labour and how to develop treatments to prevent it.

Mrs Brown told BBC Scotland: “For Gordon and I, losing Jennifer was the greatest loss and it’s one that stays with us. That doesn’t change.”

She added: “What I realised was that there was more we needed to understand, that I didn’t have answers for what had happened and so many other families didn’t either.”

The couple received more around 13,000 letters of support, many of them from people who had similar experiences. It prompted Mrs Brown to want to do more to look into the causes and consequences of premature birth.

The laboratory has been drawing on data from the Theirworld Edinburgh Birth Cohort research programme which was launched at the facility in 2015.

The study is tracking the development of 400 people as they grow into adulthood and aims to provide insights into the long-term effects of early labour on the developing brain.

Mrs Brown, chairwoman of the Theirworld children’s charity that she founded in 2002, said the study has shown the “stark realities” of the impact of poverty, which researchers have found has an impact on brain development.

She hopes the research will help other families in the future.

Mrs Brown told the broadcaster: “I would go back to the beginning and have it all change and not end the way it did for me, but I know that what it’s done has opened up other horizons.

“I would love to think that other families can avoid that loss, or if they have a baby that’s born prematurely and more vulnerable, or coming out of circumstances that are much more precarious, that there’ll be a better way to track that future and to open it up and to be able to be much more predictive about what we can do.”

Prof James Boardman, from the University of Edinburgh and the cohort's chief investigator, said a key finding to date was poverty had an impact on brain development.

A total of 400 families are taking part in the study. Of those, 300 have pre-term babies, while the remainder are full-term births.

"We have decided to study in great detail the hows and whys of why premature birth affects the developing brain," he told the BBC.

"We think it's crucial to understand the hows in order to develop new treatments and new ways of supporting that group of children."

Prof Boardman added: “It would be fair to say that a baby born at full term to a more deprived couple has a similar sort of risk of developing some developmental difficulties as a baby born at 25 weeks into a well-to-do family.”