It started as a small thing, really -- a simple effort in Chicago to celebrate American Heart Month by having folks knit or crochet tiny red hats for babies born in February.

That was in 2014, when the American Heart Association and the Children's Heart Foundation began their fledgling Little Hats, Big Hearts campaign by distributing 300 hats symbolizing efforts to empower moms to live heart-healthy lives and help their children do the same.

A cute idea -- who could resist a newborn in a red hat? -- but no one could have guessed it was just the start of a successful campaign to raise awareness, provide resources and spread information about congenital heart defects.

This coming February, more than 100,000 babies born in nearly 700 hospitals across 43 states will receive handmade hats. More than 20,000 of those will be donated from Chicago and the suburbs, where about 7,500 babies are born each February.

Organizers say each hat is laundered and packaged with information on heart disease. In most hospitals, nurses put the hats on the baby after their first bath.

"We are still recruiting hospitals to participate and collecting hats from volunteers," heart association spokeswoman Julia Kersey said, "but it's shaping up to be another great year."

Just how great a year it will be depends, in part, on the willingness of the volunteers who make all those hats.

Sometimes it's a girl working on a loom. Sometimes it's a woman knitting on a train. Sometimes it's a mom whose own child received a hat and wants to pay it forward.

Here are some of their stories ...

At the loom

In South Elgin, 10-year-old Emily Cavallini's mother says her daughter has been "knitting her heart out" since learning about the campaign a few weeks ago.

Emily received her loom as a birthday present and taught herself how to knit and use the loom by watching YouTube videos. Then, she said, "I got to work making some stuff."

Her mom, Lynne, says once Emily heard about the hats she said, "That's a great idea. I could definitely do that."

"I've made scarves, hats and blankets for my dolls and my friends," Emily said, "so I'm excited to do something to help all of the babies."

She's already got a dozen hats ready and plans to donate at least 25 by the Dec. 31 deadline.

"I play softball and the trumpet. And I play on my iPad a lot, too, so I'm going to be busy," she said. "But I like helping people, especially babies, so I'll get them finished in time."

Lynne Cavallini said she couldn't be more proud of her daughter and how she's chosen to "give back."

"She's a great kid. She's always thought of others," Cavallini said. "The fact that she wanted to do this is absolutely wonderful, but it's no surprise because that's just how her heart is."

On the train

Some Metra commuters use their time on the train as an extension of their work day. Others use it to close their eyes and unwind before returning home. And then there's Rosemary Janisch and her balls of red yarn.

"I work in the Loop, so I have a long commute to and from Downers Grove," she said. "So I've been making the hats and knitting on the train. I have a very difficult time getting involved in things because of the time commitment of my job, so this is perfect."

Janisch is knitting hats to give back to the medical community that helped her family when her son-in-law suffered from heart issues.

"I wanted to knit this year because my son-in-law Josh, who is a Navy veteran, had a stroke three years ago because a clot passed through a previously undetected hole in his heart," she said.

"When I saw this, I put two and two together because he was 30 years old and spent five weeks in the hospital. He's healthy now. My grandchild is now 2 and I thought this was a nice way to give back."

She also recruited friends to help out. Janisch is part of an 11-member Facebook group called Red Hats Off to Newborns! where she and friends from across the country post photos of the hats they're making.

"I've got eight done. It's not a massive pile, but I'll get quite a few more done in time," she said. "And I'm definitely going to keep making them for the coming years."

Giving back

Denise Galanis' son, Chris, was born Jan. 9 with a heart defect. He received his own red hat a month later.

Now she's knitting as part of this year's campaign.

She says her son's hat was a warm reminder that someone was thinking of them during a difficult time.

Chris had open-heart surgery when he was just two days old to correct the transposition of his aorta and pulmonary arteries. He spent more than seven weeks in the hospital.

Today, Galanis said, Chris is a happy, healthy baby.

"I look at the picture of him with his hat on and realize how blessed we are to have him because we almost lost our son," she said. "I want to give back, even if I'm only able to make five hats. I'm new to it. I've never knitted or crocheted before."

Chris, she said, "went through a lifetime in two months, so I can conquer knitting these hats."