Doctors are calling for more blood donations to help New Zealand's most vulnerable premature babies.
Neonatalist Dr Max Berry says a baby can have 5, 6 or 7 blood tests a day.
"This is particulary when they are their smallest and most vulnerable.
"There is no way that their little bodies can keep up with the demands of making enough red blood cells for the growth."
New Zealand has one of the highest survival rates of babies born before 30 weeks, at 66 per cent.
Dr Berry says, "that's a huge affirmation of how good the joined-up pre-natal care is in this country."
But the need for blood is constant.
The blood service needs about 3000 donations per week with the demand for blood transfusions and there's an extra push for blood types like O-negative, which only 10 per cent of Kiwis have.
"If we have got an emergency situation we can give the O-negative blood to any baby or mother," the neonatalist says.