A Massachusetts mom is celebrating the arrival of her children —quadruplets in the form of two sets of identical twins— on Thursday.

“The babies decided to make their entrance to the world sooner than expected,” mom Ashley Ness, 35, tells PEOPLE exclusively. “I feel amazing!”

Ness' newborns were delivered after 28 weeks and two days — about 12 weeks earlier than a full-term pregnancy — and will spend roughly the next eight weeks at Mass General for Children, where they are already under the care of the staff in the Neonatal Intensive Care Unit, says a spokesperson for the hospitals.

“Everyone is doing well so far and recovering because it was a busy night,” the spokesperson adds.

A pregnancy like Ness' is a rarity of “like 1 in 10 million,” Dr. Ahmet Baschat, director of the Center for Fetal Therapy and a professor in the Johns Hopkins Medicine Department of Gynecology and Obstetrics, who is not involved in her care,previously told PEOPLE.

“If she were playing the lottery, if she’s this lucky,” Baschat said, “she would be very rich.”

Ashley Ness.GoFundMe

Ashley Ness

The phenomenon occurs when two eggs are fertilized at the same time and then each fertilized egg divides again, Baschat said. Because each split egg remains encased in its own placenta — unlike traditional quadruplets, where each of the four would represent an individually fertilized egg and be encased separately — two sets of identical twins are the result.

“It’s a high-risk pregnancy,” Baschat, a 30-year veteran of his field, said ahead of Ness' delivery. “That variety I haven’t seen. We see a lot of rare stuff, but this is the first time I’m hearing this in my entire career.”

The same goes for the ultrasound technician who first detected the group of four and delivered the news to a shocked Ness.

“I had to step out of the room to Google it to make sure,” the technician said when she returned, Ness previously told PEOPLE.

Ashley Ness.Lindsey Wakefield Photography

Ashley Ness

The last thing Ness had expected to hear when she visited her gynecologist in February with a straightforward goal — to renew herbirth controlprescription — was that she was pregnant.

It took two more weeks for her to find outhowpregnant.

“I’m havingtwins?” Ness replied to the ultrasound tech, who responded with a puzzled, “I don’t know, honey,” and then stepped out of the room.

“So she starts the ultrasound back up,” Ness says. “And she goes, ‘Honey, there’s actually four babies in here.'”

Ness is a part-time hair stylist who shares a three-bedroom home in Taunton, Mass., with her 8-year-old daughter, Chanel, and her boyfriend Val, 47, a small-engine mechanic, and his two youngest sons, Isaiah, 10, and Zayden, 7. (Val has another child, 24, who lives outside of the home.)

Ashley Ness with sons Isaiah, 10, and Zayden, 7, and daughter Chanel, 8.Lindsey Wakefield Photography

Ashley Ness

On the way to conceiving again, Ness had suffered four miscarriages.

After all that, the news came as “a big shock,” she said.

Her very first thought: “It’s twins. It’s a common thing. We got this.”

Indeed, twins run in her family. Her mother had twin brothers, her grandfather was a twin and her aunt had twins. Her boyfriend’s mother is also a twin, and his sister had twins.

But learning that she was carryingtwosets of twins? “Like, I don’t even know what I was supposed to say at that moment,” she says.

Further consultation with her fetal-medicine specialists at St. Elizabeth’s Medical Center in Boston, where Ness received care before being transferred to Massachusetts General, revealed that one set of twins would be male, the other female. It was joyous discovery that didn’t entirely mask Ness’ anxiety over having two pairs of kids who will look alike.

“It’s truly been just a blessing after a blessing,” says Ness. Even so, “I was like, oh man, I’m going to mix them up. I’m going to forget who’s who. They’re going to play tricks on me. This is going to be crazy.”

Friends stepped up to help with finances. “The average cost to raise one child is 17k per year,” they wrote on aGoFundMe pagethat has raised more than $14,000. “The average cost for quadruplets is above 68k. These expenses do not include specialized treatments for preemies, which they will be. … Ashley cannot return to work as these tiny miracles will need round-the-clock care for most of their first year.”

Ness added, “I’m rearranging a lot in the house. They’ll be in my room as long as they have to because, unfortunately, I don’t have a room for them. And we have to get a new vehicle because we can’t – I mean, obviously you don’t have an eight-passenger, nine-passenger vehicle just lying around.”

“We’re fortunate,” she continued. “We have two vehicles, so we’ll have to take two vehicles everywhere we go. But I’m like, that’s the least of my worries right now. My main concern is to be able to save every little bit so we can build an addition, so the babies have a room.”

One concern she doesn’t have: Naming the babies. Before they were born, all four already had names waiting for them. Keeping with a family tradition that starts names with the letters CH, she decided the two girls will be Chesley and Chatham, and the two boys will be Chance and Cheston.

“My sister actually started that whole thing, and she had three children that all three of their names begin with C-H,” Ness says. “So when I fell in love with [daughter] Chanel’s name, I was like, ‘Perfect, it’s a C-H name.’ We can keep that going. And then, when I found out I was having four, I’m like, ‘Oh, I’m not changing it now.’ It was very challenging, though, to find four names.”

Fortunately, her boyfriend is already “an amazing dad,” she says. But his stomach wasn’t strong enough to hang around for the births this time around.

“He stayed outside in the waiting room,” Ness says. “Poor thing has a very weak belly for that stuff but when he saw them after, his heart melted.”

source: people.com