Zoe Koz has braces, rolls her eyes at her parents' jokes and loves to swim. She epitomizes a sixth-grader in almost every way — except that she happens to be the physical size of an average second-grader.

Zoe has come a long way from January 2004, when she was fighting for her life in the Edward Hospital Newborn Intensive Care Unit (NICU). At the time, born prematurely weighing 10.8 ounces, Zoe was the third-smallest baby ever born in the United States and the ninth-smallest in the world.

While Zoe may feel and act like a typical 11-year-old now, the fact that she not only survived infancy but has consistently grown and developed is not lost on her mother, Tammy Koz. For Tammy, it's like Zoe's birth and five-month stay in the NICU just happened.

"She’s really taught me not to take things for granted and to just really appreciate every day," Tammy said, her voice thick with emotion. "I know how lucky I am to have her."

When she was 18 weeks into her pregnancy, Tammy and her husband, Eric Koz, were given heartbreaking news about their girl: she was barely growing. They were given the option of going home and waiting, in hopes that Zoe would mature enough to survive outside the womb, even though they risked her dying in the womb.

According to Bob Covert, MD, medical director of Edward’s NICU and part of DuPage Neonatology Associates, Zoe’s tiny size at birth was due to a lack of blood supply from Tammy, who suffers from lupus, an autoimmune disease that causes inflammation of joints, tendons, skin and other connective tissues and organs. The lupus is believed to have caused her placenta to improperly develop.

"We went in every other day to make sure there was still a heartbeat," Tammy said. "When we got to 27 weeks, we went in for an ultrasound and the baby was still alive.” They thought, 'We've risked this long enough.'

Zoe was born by cesarean section on Jan. 6, 2004. She was frighteningly small. Her parents could slide Eric's wedding ring up her bicep. Yet, by the end of January, she was able to grasp her mother's fingertip with one tiny hand.

"Everyone has to understand that Zoe is incredibly unique," said Dr. Covert. "She was born at 27 weeks, but, because of her growth-restricting condition, she was smaller than a 23- or 24-week-old."

Her size also created technical problems — feeding tubes, breathing tubes and IVs are not made that small, Dr. Covert says. "In babies that small, with specialized conditions like Zoe, there are few survivors,” says Dr. Covert. And if they survive, they often have lifelong disabilities or illness, he added.

Fortunately for the Koz family, Zoe's stay in the NICU was relatively uneventful. Scary, yes, said Tammy, but Zoe steadily outgrew the devices keeping her alive. The tiny girl finally came home on June 9, 2004, an event celebrated by the Koz family as well as her caregivers at Edward. She's been growing ever since.

The only lingering health issues Zoe tackles with today are hearing aids and glasses. "She is a very normal, pint-sized, fun-loving girl who does well at school, socially and academically," said Zoe's pediatrician since birth, Chad Olsen, MD, with Millennium Pediatrics in Naperville. "She brightens up the office when she comes in with her sister and her family."

While there's no proof that a baby's personality can give them the fight to pull through a difficult infancy, Dr. Covert said he believes it plays a part. "Zoe was a very spunky baby, and there were a lot of maturity factors about her that surprised us," he said. Zoe also got a head start by receiving quality medical care before she was born, such as steroids to boost her lung maturity.

Tammy and Eric had a second daughter, Faith, now 6, who Tammy carried to full term with no complications.

Learn more about the Level III NICU where Zoe received care after she was born.

Learn more about high-risk pregnancies.