The world's first test-tube baby celebrates her 40th birthday this month. Louise Brown was the first of more than six million IVF babies worldwide, including many born to overjoyed families in Norfolk and Suffolk

Philipa was 18 when she met Adam. They wed four years later and started trying for a baby immediately. After a year the couple, of Ormesby St Margaret, near Hemsby, sought advice from their GP, and after another year without a pregnancy were referred for hospital tests.

For Philipa and Adam Shepherdson, like a quarter of couples being investigated for infertility, no reason could be identified.

'I felt as though something inside me was failing and it was disheartening that I didn't know what,' says Philipa. 'I felt frustrated. I had been put on fertility drugs and prodded and poked about and I still had no definite reason for not getting pregnant.

They were referred for NHS-funded IVF treatment and chose Bourn Hall Clinic in Wymondham.

To their delight, Philipa fell pregnant. But at the 12 week scan the couple discovered Philipa had suffered a miscarriage. 'It was one of the most devastating moments of our lives,' said Philipa.

There was more heartbreak when a second round of treatment failed. 'We hadn't had any embryos left to freeze after our first two treatments, and so this really was our last round and our last chance. Third time around we were given a completely different treatment plan with different drugs – and thankfully I got pregnant.'

Attending the confirmation scan was a nerve-wracking experience but Philipa said: 'When everything with the scan was fine I was crying my eyes out with relief.' Seven months ago they welcomed baby Sully into their lives.

'IVF is just the most amazing thing,' she said. 'I just hadn't realised before what goes into IVF and how over the years it has developed. There are so many different ways now of helping both women and men with fertility issues. It amazes me that we have our own IVF baby, it is just mind-blowing.'

Louise Brown was born on July 25, 1978, in Oldham, as a result of the work of gynaecologist Patrick Steptoe and research scientists Robert Edwards and Jean Purdy.

Robert Edwards and Patrick Steptoe set up the world's first IVF clinic in Bourn Hall, Cambridgeshire.

IVF treatment involves stimulating the ovaries to increase egg production. The eggs are collected to be fertilised with sperm and the resultant embryos are developed in the laboratory for five days before being frozen or transferred to a woman's womb.