Kiwi actress Narelle Ahrens' baby required two life-saving blood transfusions before he was born.
And, as his blood levels continued to fall after birth, three more transfusions were needed.
Now, Ahrens, who has played roles in Lord of the Ringsand TV drama Nothing Trivial, has made the decision to become a plasma donor, as a way of saying thank you to the New Zealand Blood Service and helping mums-to-be protect their babies.
"I just really felt I owed some people some blood. People who donate blood have saved the life of my little boy," she said.
Ahrens is sharing her story as the New Zealand Blood Service launches its annual blood donor drive - this year dubbed "Know Your Type" - where it hopes to recruit 20,000 new donors.
Each year the lives of about 27,000 people in New Zealand are either saved or improved, by blood donations.
When Ahrens was 28 weeks pregnant with her second son Micah, now 3, she had a routine blood test that showed her body was producing antibodies.
A second blood test about two weeks later revealed Ahrens' antibodies had "shot through the roof" and she was quickly referred to the Maternal Fetal Medicine department at Auckland Hospital.
"It all got quite scary and frightening quite quickly," she said.
Ahrens and Micah's blood had mixed and, because they have different blood groups, her immune system was producing antibodies to destroy her son's foreign red blood cells, making him anaemic.
"It's a really strange feeling to know that you are sitting there and you are fine but while you are sitting there your body is attacking your baby, the baby you want very much, and there is nothing you can do to stop it," said Ahrens.
Micah was at risk of a heart attack, brain damage or even dying.
An intrauterine blood transfusion was carried out to replace Micah's red blood cells and keep him healthy until he was mature enough to be delivered.
But, at about 34 weeks, Micah was showing signs of being anaemic and distressed again, meaning he needed a second intrauterine blood transfusion.
"That second time felt more extreme. I felt like maybe I was going to have contractions," said Ahrens, who was told the procedure could cause her to go into labour.
"I think I thought it would all be okay when he was born since he had the extra blood," said Ahrens.
But the nightmare continued for Ahrens and her husband, Julian Wilson, when Micah was born. His body still had blood from Ahrens, which continued to make him sick.
"We had an hour [after he was born] just thinking everything was going to be okay and giving him a cuddle. And then suddenly he wasn't okay," she said.
Micah was rushed to Auckland Hospital's neonatal intensive care unit with haemolytic disease of the newborn, a blood disorder that caused him to develop jaundice and anaemia.
He was put in an incubator under fluorescent light for four days.
"I couldn't hold him, I couldn't feed him, I couldn't take him out of that incubator away from the lights. At the point it was so serious that if keeping him under those lights didn't work they would've had to perform a blood exchange - where they would have to take all the blood out of his body and replace it with new blood."
Micah was transferred to Waitakere Hospital's specialist care baby unit where the tired, jaundiced and weak baby's blood levels fell again, requiring another blood transfusion.
"He was limp and kind of grey and very weak and then they organised this blood transfusion and basically you just watched your baby pink up in front of your eyes," said Ahrens.
This became the first of three blood transfusions Micah had in the next three months.
But "just like magic", as Ahrens put it, at 3 months old Micah was fighting fit once all the antibodies had finally left his system.
About two years ago, Ahrens made the decision to become a plasma donor as a way of saying thanks for the lifesaving blood transfusions Micah received.
Her plasma has been used to make the anti-D injection, which is given to pregnant women so they do not produce the antibodies that can attack their baby's blood, like Ahrens did.
Although Ahrens had the anti-D injection when she was pregnant with her first son, Oscar, it was too late as their different blood types had already mixed.
Oscar, now 7, was fine. However, when Ahrens' body detected foreign blood for the second time, when she fell pregnant with Micah, her immune system was fast to react.
Ahrens said giving plasma felt like "the right thing to do", to help others in the same way blood donors who helped save her "snuggly" little boy's life had.
New Zealand Blood Service's national marketing and communications manager Asuka Burge said that between 2002-17, 100 women have been given intrauterine transfusions, totalling 415 units of red blood cells.
"The need isn't on the rise , but we still need to ensure we have an adequate pool of donors who meet the usual criteria for donating," she said.
Criteria for donations that could be used for intrauterine transfusions include O blood group Rh negative (9 per cent of the population) .
>> NZME is the official media partner of the New Zealand Blood Service's Know Your Type campaign
Know your type - and save a life
The New Zealand Blood Service (NZBS) is running a series of Know Your Type events over the next week allowing Kiwis to find their blood type and become a donor.
Every year, the NZBS needs 20,000 new donors to step up and find out if they are the type to save a life.
Go to one of the events around the country, find out if you meet the criteria and one of the Blood Service's staff will test your blood through a quick finger prick. Within a couple of minutes, you'll know your type and you can register to donate.
Preference for blood typing will be given to those who meet the donor eligibility criteria, which can be found here.
The Cloud, Queens Wharf
Saturday 14 October and Sunday 15 October 9am-4pm
Westpac Atrium, Britomart
Wednesday 18 October 10am-2pm
Bayfair Shopping Centre, outside Kmart
Saturday 21 October 9am-6pm
Chartwell Shopping Centre, level 1
Tuesday 17 October 10am-2pm
Te Papa Museum foyer
Wednesday 18 October 11am-2.30pm
The Blood Donor Centre, Addington
Monday 16 October-Friday 20 October during centre opening hours
Cashel Street Mall
Friday 20 October 11am-2pm
Thursday 19 October 11am-1.30pm
Red gold - The gift of life
• New Zealand donors gave blood 164,000 times between July 2016 and June 2017.
• Last year donors saved and improved the lives of 27,000 New Zealanders - about 74 people a day.
• One blood donation has the potential to save three lives.
• You can donate blood every three months.
• About 20,000 people leave the donor registry each year, for a number of reasons including age, ill health, pregnancy and overseas travel. Those donors have to be replaced to keep up with demand.
• The red cell component only lasts 35 days, while platelets must be transfused within seven days of collection. Plasma can be frozen for up to two years and blood products made from plasma can be stored for up to two years.
• More than 50 per cent of Kiwis don't know their blood type.
• Just 4 per cent of the eligible population are donors.
• 85 per cent of our population are A and O blood groups, the types most in demand
Source: The New Zealand Blood Service