A three-year-old boy who would almost certainly have been born paralysed because of a severe spinal abnormality is able to walk after having ground-breaking stem cell surgery while still in the womb. Scientists say a world-first treatment for a severe form of spina bifida in babies is safe and effective. Surgeons in California used stem cells to repair six babies' spines after surgery -- while they were still in the womb. Sky's science correspondent Thomas Moore met Tobi, the second child ever