While all babies benefit from breast milk, it can be the difference between life and death for premature babies. The nutrients, hormones and growth factors found in human milk are essential to their healthy development.
It helps their immune systems fight viruses and bacteria and protects them against necrotising enterocolitis (NEC) -- a life-threatening bowel condition common in premature babies. Many will need life-saving surgery, and often this can only be performed on babies fortified by human milk.
But, at a time when it is most needed, many mothers are unable to produce milk for their baby.
Since it opened in 2000, the Milk Bank in Irvinestown, Co Fermanagh, has provided human milk for 5,514 premature and sick babies all across Ireland. Many of these babies would have died without this help.
However, the Milk Bank can only do this through the kindness of its donors: breast-feeding mothers who give some of their milk so that other mothers can feed their sick babies.
Ann McCrea is the co-ordinator and founder of the Milk Bank. In 1999, she was part of a team that was caring for a premature baby whose mother was unable to produce milk.
"He started to show signs of NEC," says Ann. "We were treating him with antibiotics, but he really was an at-risk child. We knew that if we could get breast milk for him it would help protect him against NEC."
But, there were no milk banks in Ireland, and those in the UK had no milk to spare. Ann clearly remembers her sense of frustration at the time.
"'Hang on,' I thought, 'Irish babies need looking after -- the same as other babies. So why don't we have a service that will protect little children like this?'"
Ann spoke to everyone who might have some relevant expertise: paediatricians, dieticians, laboratory staff and those involved in transport services.
"We came to the conclusion that, yes, we can do this."
The Milk Bank had very humble origins.
"We started off with a kitchen. It was a small kitchen with room for one person. It had a freezer for storing milk, a fridge for defrosting it, a pasteuriser, a sink for washing up and a sink for hand washing."
In the early days, Ann's team provided milk for babies in the local area. But soon, hospitals throughout Ireland started requesting their help. The Milk Bank grew to meet this need.
"We now issue about 1,000 litres of milk a year to hospitals throughout Ireland," Ann says proudly.
So, why do some mothers need donor milk? Quite often it's because some babies are so premature that their mothers have not yet started producing milk. Sometimes mothers have conditions that leave them unable to breastfeed. And in other cases, it's because mothers are separated from their babies.
"We had twins born in Belfast who had to be transferred to a hospital in Glasgow because of a shortage of neonatal beds," says Ann. " And we had an incident with triplets who were being treated in two hospitals in Dublin while their mother was being treated in Galway."
Because they're not with their baby, some mothers can struggle to produce milk, explains Ann.
"For a mum to pump well, she needs to be with her baby, looking at her baby, feeling and smelling her baby."
Stress can also be a factor. Stella Kraft needed help when she developed pre-eclampsia and her daughter had to be delivered by Caesarean section at only 31 weeks.
"My daughter was really, really tiny, and I couldn't produce enough milk to feed her," says Stella. "Having such a small child, knowing that she really needs you and you can't give her what she needs, that builds up pressure."
This pressure further interfered with Stella's ability to produce milk. Fortunately, the Milk Bank was able to help immediately.
"It was a big relief to get donor milk. I knew that my daughter was being fed, and was getting everything she needed until I could feed her."
This intervention helped reduce Stella's anxiety, and after a few days she was able to produce enough milk to feed her baby.
As well as its proven benefits for premature babies, breast milk is also vital for newborns needing surgery. It helps prevent post-operative infections and can also increase the chances of success in certain procedures.
"Heart surgery babies need breast milk to protect against NEC. In years gone by, surgeons would perform wonderful surgery, but the babies were dying of NEC because they'd been given formula," explains Ann.
"The drugs for heart conditions and blood pressure work much better when babies are breast fed.
"For gut surgery, breast milk is very important. It has all the growth factors in it, and breast-fed babies have a longer gut. This gives the surgeons more to work with."
However, the Milk Bank can only help these babies through the generosity of their donors: breast-feeding mothers.
Rachel Tyrrell Lane had wanted to be a blood donor, but couldn't. So, when she had her daughter, she saw this as an opportunity to help others.
"I found I had an abundant milk supply and decided to look into donating some," says Rachel. "I knew the amazing benefits of breast milk for babies, particularly for babies born prematurely or babies who are unwell. I wanted my milk to help others, so I got in touch with the Milk Bank."
Rachel began donating and found her efforts instantly rewarding. She was also surprised to discover that she was following a tradition in her family.
"My grandmother told me that when she was nursing her children, a nurse would call and collect milk in a metal jug to give to the sick babies. I come from a family of donors!"
Sinead McVitty became a donor after she had been struggling to feed her own daughter, Alexa. Because she wasn't able to latch on properly, Alexa was 11 days old before she could be fed exclusively with breast milk. During this time, Sinead was expressing milk and storing it in her freezer.
"I happened to hear one of the girls at the breastfeeding group I go to say the Milk Bank was really keen to get new donors, because their supplies were quite low," says sinead.
She contacted the Milk Bank and offered them her stored milk. After passing their health checks, Sinead's offer was gratefully accepted.
However, Sinead was already aware of the importance of breast milk for premature and sick babies. For incredibly sad reasons, this was a special moment for her.
Back in February 2012, pregnant with twins, Sinead went into labour. Her waters had broken 11 days earlier, only 26 weeks into the pregnancy, and she had been rushed to the Royal Victoria Hospital in Belfast.
"I had my first twin, Corey, at 19.17. I delivered him normally. But my second twin was transverse -- she was horizontal. So I had an urgent Caesarean section. She was born 34 minutes after Corey and we called her Alanna."
Corey weighed only 2lb 6oz, while Alanna was slightly heavier at 2lb 7oz.
"There were a lot of people in the room. They only gave me a brief glimpse of my babies before rushing them to the neonatal intensive care unit."
By the next morning, Corey had become very ill and Sinead and her partner were advised to have him baptised. Despite this, she still hoped for the best.
That evening, Sinead took her mum to see the twins.
"Their incubators were beside each other. The nurse asked if I wanted to touch them. I did, but I was so scared I was going to hurt them. They were so tiny and fragile.
"I put my finger in Alanna's hand. I'm nearly sure she gave it a squeeze -- and she opened her eyes. Corey was sedated. I put my hand in and felt his wee shoulder."
As the night progressed, Alanna also became very ill.
"She'd gotten so ill and wasn't going to pull through. The neonatologist advised us to switch off her machine."
On the morning of February 20, 2012, Alanna passed away.
Later that day, Corey's condition worsened. He wasn't going to survive. For the second time, Sinead and her partner were advised to switch off the life support of one of their children.
On February 22, 2012, Corey and Alanna were buried together.
"Had my twins lived, they would have been reliant on milk from the milk bank. I understand how important it is to sick and premature babies.
"I donate milk in memory of my twins. The feeling I get, knowing I'm helping other children, is quite special."
The magnitude of what the donors provide is not lost on Ann McCrea. Each small bottle of donated milk can feed six sick or premature babies -- no matter what part of the island they live on.
"It's precious milk for precious babies. Without our donors' hard work we would never have been able to help 5,514 babies in our first 12 years," she says.
"They're not just mothers -- they're superwomen!"