People who have been in accidents and suffered massive blood loss may need multiple transfusions of red blood cells.
Thousands of healthy babies thanks to Graeme's dedication.
Graeme Thomas, one of New Zealands most dedicated blood donors, made his milestone 500th blood donation in 2010.
No one else in New Zealand has given as much blood as Graeme 350 litres over the past 42 years.
Through his fortnightly donations of plasma, a component of blood, Graeme has helped more than 5,000 New Zealand mothers to have healthy pregnancies and give birth to healthy babies.
"You wouldnt know that Graeme Thomas has helped so many mothers and babies, but this is the power of blood donation", says Fiona Ritsma, Chief Executive of the New Zealand Blood Service.
As a blood donor, Graeme has made simple and regular gesture that has had a profound impact on many lives. His generosity has ensured thousands of healthy babies and happy mothers.
Graemes donations are used to make the Anti-D Immunoglobulin injection, which is given to many mothers to stop their babies suffering from Haemolytic Disease of the Newborn (HDN).
Graeme began donating blood on a regular basis in 1968, as part of a programme started to fuel the production of the Anti-D injection in New Zealand.
"I answered an advertisement in The New Zealand Herald newspaper calling for male blood donors with a Rh negative blood type. I had given blood a few times as a student, so it was something I was accustomed to", says Graeme.
Men were sought for the programme because they could produce the antibodies needed and provide ongoing blood donations without the risks associated with immunising women.
Around 9,000 NZ women need an Anti-D Immunoglobulin injection each year. It mops up foetal Rh positive red cells that can pass through the placenta, so that a mother with a Rh negative blood type does not produce antibodies against those cells. If the mother produces antibodies, they attack the Rh positive red cells of that foetus and those of possible future pregnancies.
Specialist Transfusion Nurse with the New Zealand Blood Service, Rachel Donegan, says that prior to the development of Anti-D, there were often cases of babies born with life threatening jaundice and anaemia.
"Prior to Anti-D, babies with bad cases of HDN developed acute anaemia and many died. Those who survived often had severe jaundice and would require full blood transfusions, sometimes 10mils at a time", says Rachel.
In keeping with Kiwi culture, Graemes reason for being such a dedicated blood donor is simple and straight to the point: Well, its worthwhile, and its easy! he says.
In his younger years, Graeme would walk to Grafton Hospital to make donations on his lunch break from his administration job at Auckland University.
Now retired, he travels by ferry and then train to the Epsom donor centre from his home in Devonport on a fortnightly basis.
"It takes me a while, but it suits my retirement lifestyle", says Graeme.
Graeme says he likes that, as a blood donor, you never know when you could be called upon, or when your blood might be being used to save a life.
"It is such a big thing to save a life, yet it is such an easy thing to donate blood."