During three operations Manon Elis needed 18 units of blood to save her life after complications when her daughter, Cadi, was born.
She says without the blood she would not be alive today.
NHS Blood and Transplant is urging donors to make a special effort to keep appointments during the bad weather.
Ms Elis, who plays Michelle in the S4C drama series Rownd a Rownd, had an emergency Caesarean section after her labour failed to progress properly.
She said at first everything appeared to be fine and she remembers cuddling her new daughter and trying to breast-feed her.
"Then all this blood came and they said I'd have to go back for more treatment," she said.
That treatment last five hours and resulted in a hysterectomy.
"That saved my life and I came round in intensive care," she tells BBC Radio Cymru's Manylu programme.
However the bleeding began again and she had to endure a third operation.
"In the meantime I'd had 18 units of blood - given by 18 people I can never thank personally - without which I would not be here," she added.
With her baby, now six months old, playing nearby she said she is gutted that she is now unable to give blood herself.
"The only thing I can do now is to tell my story, so that encourages other people to donate," she said.
Ms Elis said the weather might be putting people off going to give blood during the winter months.
"Maybe they don't look at the big picture, and I've been surprised how many people have told me they have thought of giving blood but never done anything about it," she added.
The recent bad weather resulted in 2000 fewer donations being made in just one day at clinics across England and north Wales.
Jon Lathan, assistant director of Blood Donation, at NHS Blood and Transplant (NHSBT) said the volunteer donors were vital to maintain blood supplies to hospitals.
"We need to make sure that we make the most of the sessions that are going ahead to try and make up for the losses in other areas," he said.
"If you have an appointment please try to keep it and if, for some reason you cannot, please re-book your appointment as soon as possible. New donors are always welcome too," he added.
The full story can be heard on BBC Radio Cymru's Manylu programme at 1800 GMT on Monday 10 January.
A Caernarfon-based actress is backing an appeal for blood donors after her life was saved during surgery after child birth.