Doctors in the UK have performed groundbreaking surgery on an unborn baby diagnosed with spina bifida. 

Bethan Simpson, 26, was told that her unborn baby Eloise had the condition after a 20-week scan revealed that the baby's head was not growing as expected. Spina bifida affects the development of the spinal cord and can cause problems with walking and movement. 

The spinal surgery was carried out on Eloise by surgeons at University College Hospital in London at only 24 weeks when she was still in the womb. 

Bethan and her husband Kieron had reportedly been given the option of aborting baby Eloise or trying the relatively new procedure, which has only been performed three times before in the UK. 

'We were offered continuing pregnancy, ending pregnancy or a new option called fetal surgery – fixing her before she is born. We had to do it,' she wrote on her Facebook page.

'Our lives were such a rollercoaster for the next few weeks.'

The surgery involved carefully opening Bethan's womb to expose the baby's back in order to make repairs to the spinal cord before closing the womb up again.  The procedure is similar to a caesarean section except that the baby is returned to the womb instead of being removed.

Although it is still too early to tell what impact the surgery will have on Eloise's development, Bethan is optimistic for her daughter's future and is encouraging other parents in the same situation not to see their child's diagnosis as a 'death sentence'. 

'We were a success. Her lesion was small and she smashed surgery like you wouldn't believe. I'm fragile and sore but as long as she is doing fine that's all we care about,' she said. 

'Sadly, 80% of babies in England are terminated when their parents get told their baby has this condition. It's not a death sentence. She has the same potential as every one of us,' she added.

'Yes, there are risks of things going wrong but please think more about spina bifida, it's not what it used to be.

'I feel our baby kick me day in and day out, that's never changed. She's extra special, she's part of history and our daughter has shown just how much she deserves this life.'