Newsroom lore says nothing pushes readers' buttons quite like a good animal story. Lately we've discovered restaurant openings and closings draw a big online crowd.

Add one more item, thankfully a human one, to the list: Newborns in knitted red hats.

We discovered this in November, after posting a story submitted by the American Heart Association to kick off the Chicago area's Little Hats, Big Hearts campaign for February, American Heart Month. The association was asking people to knit or crochet red hats in newborn and preemie sizes. Even gifts of yarn were welcome. The point of it all was to promote awareness of congenital heart disease that strikes 40,000 newborns each year, something that can be diagnosed with a simple, in-the-hospital test.

Oh. And the story was accompanied by an incredibly cute picture of a baby in one of those red knitted hats.

One advantage of the digital age is it's pretty easy to see a particular story's popularity. We can measure page views, number of "hits" on a particular item, number of times it's "shared." We also can move the process along when we "tag" someone or some institution if we think they're likely to share the story. In this case, it was the American Heart Association, reasonably well-known in some quarters.

Soon afterward, "We noticed a huge uptick in calls to our office about the Little Hats, Big Hearts program," said heart association spokeswoman Julia Kersey. "The calls were coming from around the country, and we eventually traced them back to the Daily Herald piece."

As I write this, the story has been liked or shared more than 16,000 times. Impossible to say how much of an impact our post might have had, but something we often say -- "We have the nicest, most altruistic readers" -- seems to hold true again.

When the program was launched in 2014, the heart association had 300 hats to distribute; now the number is 19,000 and they're standard issue at many hospitals.

Against that backdrop, we heard about a West Chicago mom whose son was born with multiple heart defects. After surgery on his seventh day of life, he requires careful monitoring but is doing reasonably well at 18 months, staff writer Justin Kmitch wrote in Saturday's editions. His mom, Samantha Witt, knew nothing of the heart problems that can affect so many newborns. Today, though, she eagerly assists with the distribution of the little hats for new babies at Delnor Hospital in Geneva.

"I'm knowledgeable now," she told Kmitch, "and I want to do anything I can to help babies who fought like Mason has had to and their parents so they don't feel as scared and alone as I did."

Now that's a story well worth sharing.