Zoe Koz is still small, fiesty as she approaches fifth birthday

Zoe Koz is acting silly.

She's speaking in a whispy, high-pitched voice proclaiming her age to be "just" two.

"And that's it," she says.

But she's not.

Just looking at her, it seems believable. She's about the height of the average 2-year-old. And because her idea of a big meal is two bites, she weighs what an average 1-year-old does.

"She'll pull that two-bites-and-I'm-full bit, but she comes back pretty soon wanting a snack," her father, Eric, explains.

Zoe Koz may not be your average-size soon-to-be 5-year-old, but she acts exactly like one. Chatty, inquisitive and seemingly growing more independent by the hour, Zoe is pretty normal. And that's the best diagnosis her parents could have ever hoped for.

It's been almost five years since Zoe entered the world at Naperville's Edward Hospital as the third-smallest baby ever born in the U.S. to survive - she weighed just 10.8 ounces and was only 9.5 inches long. She was born Jan. 6, 2004, three months and three days before she was supposed to arrive. Her mother Tammy's lupus caused the placenta holding Zoe to develop improperly.

"I really didn't have any expectations after she was born, so everything has surprised me because I really didn't know what to expect," Tammy Koz said. "Every little milestone with her I made a big deal out of because she's my miracle."

To be fair, everything looks small inside Zoe's big pink bedroom at her house in unincorporated Will County between Plainfield and Joliet. However, Zoe looks particularly tiny flitting between toys, dolls and other attractions in the room. She finds a box filled with miniature plastic animals and pulls one after another out while reciting their species.

Her parents say the little girl's favorite playthings are often smaller toys, perhaps to make her feel bigger. She even walks on her tiptoes, which give her an extra inch or two in height.

"She always wants to do what the big people are doing," Eric Koz says. "That could be the reason she walks on her toes, just to look taller."

Zoe is one of five children Tammy Koz looks after on weekdays at her home-based day care, but her mom thinks of her as kind of an assistant.

"She's a little mommy," Tammy Koz says.

The experience with little ones is going to come in handy now. Zoe is about to become a big sister. The Koz's were scheduled to welcome their second daughter Tuesday. The baby girl also was going to be premature, but this time it was on purpose and by only a few days.

"We knew why Zoe wouldn't grow, so it wasn't a shot in the dark this time," says Tammy Koz's obstetrician Dr. Julie Jensen.

Doctors upped Tammy Koz's anticoagulants and her doctor visits are triple the normal expectant mother's.

"She's to the point where we see her once a week," Jensen says. "She's getting followed pretty darn closely."

With all the drama surrounding Zoe's birth, this pregnancy was remarkably unremarkable.

"There wasn't one complication with this pregnancy," Tammy Koz insists.

But that's not to say Eric and Tammy Koz didn't live in a heightened state of concern. The sound of someone knocking on wood was fairly common inside their home.

"I did it the other day," Eric Koz says. "We did it all the time."

The couple says this is likely their last child.

"We wanted Zoe to have a brother or sister," Tammy Koz says. "I think we're extremely blessed to have what we have."

Zoe's parents say there were so many people who wrote letters and sent gifts after Zoe's birth that they just want everyone to know how well their little girl is doing and how thankful they are for the support and well-wishes of so many strangers.

People still recognize the family when they go out. A clerk at a store will see the name on a credit card or someone will hear Tammy Koz calling out her daughter's name.

"The first year or two people recognized us by looking at us," says Tammy Koz. "It's rare to find someone who doesn't know her story."

It's going to be hard to beat Zoe's story, but the new baby has a pretty neat prologue as well. The couple was planning to adopt earlier this year after Tammy Koz suffered a miscarriage.

"We had met with an attorney and scheduled a meeting with a fairly well-known adoption agency and we showed up and nobody from the adoption agency was there," Tammy Koz says. "They never called us. They completely forgot about us. Then oddly enough, three days later I took a pregnancy test and I was pregnant."