Couple welcomes quadruplets 4 years after birth of their twins

Monitoring Desk

CALIFORNIA: Callie and Gabriel Smith had already welcomed three children when their quadruplets arrived in June, but in some ways, the California couple’s new babies made them feel like rookie parents.

“It feels like they’re our first kids because they’re our first preemies,” Callie, 36, tells PEOPLE exclusively.

“It’s definitely been a learning curve,” the mom of seven adds. “We’ve had to readjust our expectations and we’re just constantly trying to figure it out as we go.”

When the Smith babies — Norah, Selah, Ezra and Abigail Smith — were born nine weeks early on June 16, their birth was a seamless operation, according to neonatologist Dr. Huy Truong.

“The delivery could not have gone better,” Truong tells PEOPLE. “After all the preparation and other precautions, it all occurred without any hiccups.”

Truong says those on call anticipated that the babies would require oxygen and feeding tubes when they were born, and the quads spent time in the NICU at Kaiser Permanente in Fontana, learning how to breathe and eat on their own over a 40-plus day stay.

Norah and Selah went home together at the end of July, while Ezra and Abigail left the hospital about a week later, Callie says.

But due to feeding issues at home, Abigail soon returned. She later underwent successful surgery to close a blood vessel, which runs from her pulmonary artery to her aorta, according to Truong.

Now, weeks later, the babies are settling into a routine at home in Upland as their parents reflect on their initial plan to add just one more baby to their brood, which includes Ariella, 7, and twins Noah and Samara, 4.