The NHS is urging people with O negative blood to check whether their family members also have it and encourage them to donate.
There is a huge demand for the blood because it’s universal and can be given to anyone in an emergency, regardless of their own type.
But it’s also the rarest, meaning demand far outstrips supply.
NHS Blood and Transplant (NHSBT) said hospitals need an increasing amount of O negative blood which can be used for car crash victims and newborn or premature babies.
O negative now makes up 14 per cent of all the blood issued to hospitals, the highest ever level, despite only eight per cent of the population having it naturally.
‘We need an ever growing share of our blood donors to be O negative to meet hospital demand,’ said Mike Stredder, director of blood donation at NHSBT.
‘If you are O negative, please talk to your family and share your story. There’s a one in three chance they are O negative too.
‘O negative is essential for saving people’s lives in emergencies because the red blood cells can be given to almost anyone.’
NHSBT said the long-term demand for O negative is mainly being driven by the need to substitute O negative for a rare blood type called Ro.
Ro, a subtype blood group, is more common in people of black heritage, and only two per cent of regular blood donors have Ro.
There is a rise in the number of people with sickle cell disease with Ro blood who need regular transfusions.
NHSBT is also appealing for new male donors after revealing the number of men giving their blood in England has fallen by around a quarter over the last five years.
It said men’s blood, which is higher in iron than women’s, is able to help more patients with each donation.
Sebastian Cockerill, now aged six, was born by emergency Caesarean 15 weeks early at 25 weeks into pregnancy.
His bone marrow was not mature enough to produce enough red blood cells to keep him alive.
He received several lifesaving blood transfusions at Luton and Dunstable University Hospital’s neonatal intensive care unit including one with O negative blood from 43-year-old Andrew Spence, from Corby in Northamptonshire.
Seb and mother Helen, 41, from Sudbury in Suffolk, have now met Mr Spence.
Seb gave him a big hug and presented him with a card that said: ‘To Andrew, thank you for letting me have some of your blood.’
Seb said: ‘The blood was in Andrew’s veins and it’s gone into my veins. People should go and donate blood and save lives like Andrew did to me.’
Mr Spence said: ‘The day was fantastic – what an amazing, emotional experience. Seb and his mum Helen were wonderful. He truly is a remarkable young man.’
Mrs Cockerill said: ‘Seb was absolutely thrilled to meet Andrew and he has asked a couple of times now when we will see him again.
‘Seb would not have survived without Andrew and the other donors.
‘He has completed year one of school. He loves Lego and spending lots of time playing with his friends and cousins.
‘It is so amazing to see after such a frightening start to his life.’
She added: ‘I don’t think people understand how important O negative blood is. Family members of people who are O negative – please go out and get tested.’