Blood donors saved Merthyr Tydfil mum and her daughters
"I wouldn't be alive if it wasn't for blood donations, and we wouldn't be a family."
Mother-of-two Shelley Parry needed blood transfusions during both her pregnancies to keep her and her daughters alive.
The 39-year-old, from Merthyr Tydfil, believed the donation service was "critical, especially to us".
The Welsh Blood Service said blood donations were down because of Covid.
Last month Scotland had fewer registered blood donors than at any other point this century.
Before Christmas the Republic of Ireland was importing blood from England and England's hospitals got through the pandemic with the smallest pool of donors in the 21st Century.
During Ms Parry's first pregnancy with Gracie, now 13, she needed a number of transfusions from the Welsh Blood Service.
She said: "The importance of blood donation is critical, especially to us, because without it we wouldn't be a family.
"When my first daughter was born, she had jaundice and needed light therapy, but I needed several blood transfusions because I lost a lot of blood during the birth.
"[Without] the blood donations, I wouldn't be alive."
During Ms Parry's second pregnancy she received blood transfusions directly into her womb. These kept her youngest daughter, Georgina, alive.
Georgina had to be delivered early, at 33 weeks, and needed an intrauterine transfusion, which is when a large needle is inserted in the stomach to get blood to the baby.
"She needed several top-ups too after being born prematurely so she was well enough to take home," Ms Parry said.
The pandemic meant the use of community donation vehicles in Wales was suspended because of restrictions.
Now, the blood service and Ms Parry want potential donors to come forward, especially those aged 17-30 as its usual school, college and university programmes are on hold.
"Georgina and Gracie are both leading full, vibrant and active lives, and that is down to the fact when we needed it there were blood donations," she said.
Georgina, 12, agreed: "I think it's important to give blood because it saved my life and can save so many others as well."
Welsh Blood Service interim director, Alan Prosser, said winter was always challenging, without the added pressures of a pandemic.
He said: "We were finding in late November and December our cancellation rates were going up because of the contagion rates of Omicron in the communities, and impacting on our service delivery.
"We've had to find larger venues because of social distancing, so we moved away from smaller community donation centres."
Mr Prosser said the service wanted more 17-30s to donate because they can help combat blood cancer and join the Welsh Bone Marrow Donor Registry.
Only 3% of the eligible population donate blood and the blood service said each donation had the potential to save the lives of three adults or six babies.
Swansea University criminology lecturer Dr Gemma Morgan recently gave blood for the first time.
The 30-year-old said she had been meaning to do so for a while.
"The pandemic did delay me slightly because I wasn't sure if it was happening, but I think it is about raising awareness about how important it is and how easy it is to do," she said.
Swansea University student Freddie Ward, 19, who was at a donor session at a hotel near the main campus, called the donor shortage "disgusting".
He added: "It's important to support the NHS. They have supported us through Covid."
The Welsh Blood Service collects about 100,000 donations during a typical year to support 20 hospitals across Wales.
Clinical skills facilitator, Bethan French, believed giving blood was "an amazing thing to do".
"It'll take 45 minutes out of your day and one donation could save three people's lives," she said.
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