Annmarie Byrne-Ryan and David Ryan defied the odds on New Year's Day when Annmarie gave birth to spontaneous triplets, and not just any triplets but identical triplets.

The occurrence is described as "incredibly unusual".

The chance of giving birth to three identical children is one in one million, according to Master of the Rotunda Hospital Fergal Malone.

The three boys, who have named Kyle, Max and Zach, were born just before midday yesterday in the Rotunda.

Annmarie, who is originally from Swords, speaking just hours after the birth of the triplets said the pregnancy was unexpected.

"They're doing well. I’ve yet to see all three together," she said.

"David’s been up and down, back and forward to the NICU ward taking loads of pictures, keeping me updated. So I’m anxious myself to get down to see them."

The parents will have "built-in babysitters" in their older children: David has a son named Jordan and Annmarie has a daughter named Shauna, both of whom are 18.

Together, they have Mason who has just turned two.

Speaking to RTÉ’s Morning Ireland yesterday, Annmarie said she was "a little bit tired" as she had not slept yet.

"A little bit of pain, but no I’m okay, I’m just relieved they’re here, they’re healthy and all is good at the moment anyway, thank God."

Annmarie said she was scheduled for delivery on 8 January, but her waters broke unexpectedly at home in the early hours of the morning. They came in to the hospital and things started moving quickly.

Annmarie Byrne-Ryan and David Ryan said all three babies are doing well

"It was very much a shock," she said about finding out she was pregnant with triplets.

"Because it wasn't planned. We got married at the end of April and went on honeymoon to Dubrovnik in May, and where most people come back with fridge magnets, myself and David brought home triplets!

"So we were in shock about that and we didn’t even know we were having them obviously until I had a bit of a bleed nine or ten weeks in and we came into the hospital and we found out then.

"Then it was even more of a shock to find out they were identical," she said.

"We found out later down the line that they were identical - I think it was maybe three or four months. I have only one ovary myself because I had an operation and had an ovary removed in this hospital when I was 18. So they were baffled with that as well."

"We’re blessed, absolutely blessed. It’s going to be tough, but we’ve plenty of support from both families so we’ll just have to do it," she said.

Master of the Rotunda Professor Fergal Malone said the triplets' mother is "very impressive and she's doing so well".

The new babies are described as spontaneous triplets.

"The vast majority of triplet pregnancies that we see today are a result of fertility therapy, either mother taking medications to ovulate multiple times or having IVF.

"Only about 10% of triplet pregnancies occur spontaneously, just naturally without any medication or intervention at all," he said.

Identical triplets are "incredibly unusual", said Prof Malone.

"Probably no more common than one in a million or even less. The embryo splits once into two identical twins, and then one of those splits yet again into now an identical triplet. So not only one split but two splitting to achieve identical triplets is incredibly rare."

"I think it's a big surprise when you tell a patient at seven or eight weeks that not only is she pregnant but she's pregnant with three babies in there.

"The patient will often say to you, 'well, how is that possible?'. Especially if they haven't taken any fertility treatments, and to then say well, 'it's just one of those things', that the ovary releases several eggs.

"But then when you delve a little deeper and you realise no, all three are actually identical, is particularly unusual."

Prof Malone said Annmarie did everything the hospital asked her to do and took it all in her stride.

"You would always do your best to try and deliver triplets during the day if possible, when your staffing is a little bit better than at night. So when you know that a patient is about to go into labour with triplets, or she's going into labour, you then mobilise additional neonatal resources, additional nurses and doctors to come in.

"So everyone is on standby, jumps in, and everything is done in a calm controlled manner. But it's because we're so busy we have that depth available."

Prof Malone said it was hoped the triplets would spend no more than two or three weeks in nursery before the parents can take them home.

He said everyone at the hospital is thrilled for the parents, and especially so to see the babies doing so well.

"The downside from the hospital's perspective is that the hospital is now closed to external admissions from neonatal perspective for a short while until we catch up. But that's because we're so busy anyway. So it does add a small little extra demand on us, but we handle it."

In total, there were 23 babies born at the Rotunda yesterday.