Jimmy Kimmel used his late night show's monologue on Monday to tell the story of his son's birth last week. It was a harrowing one, as Billy was born with a congenital heart defect and needed emergency surgery to fix it.

Fortunately, Billy came through OK and was able to go home after six days in the hospital. But as Kimmel explained, before the Affordable Care Act (ACA), Billy's heart defect would be a pre-existing condition — and would likely deny him the ability to buy health insurance down the road.

And Billy would have a lot of company. Anywhere between 61 million and 133 million non-elderly Americans would have fallen under the umbrella of a pre-existing condition, depending on the underwriting rules used to determine their eligibility, according to a brief from the Department of Health and Human Services (HHS).

And while Kimmel acknowledged that he's lucky enough to be able to afford the highest health care available, many other families aren't.

Under the broadest definition of the term, HHS found that 24 percent of Americans under the age of 18 had some kind of pre-existing condition. Kimmel's newborn son's heart defect certainly would have qualified under any definition of the term.

"Any of these 133 million Americans could have been denied coverage, or offered coverage only at an exorbitant price, had they needed individual market health insurance before 2014," the brief declares.

The conditions that could have denied them coverage before the ACA were among the most common around the world, including, "high blood pressure (46 million people), behavioral health disorders (45 million people), high cholesterol (44 million people); asthma/chronic lung disease (34 million people), heart conditions (16 million people), diabetes (13 million people), and cancer (11 million people)."

And for them, a return to pre-existing condition exclusions might bring on financial ruin, and brutally hard choices.

After praising the staff at Children's Hospital Los Angeles, where Billy had his surgery, Kimmel pleaded with the Trump administration and Congressional Republicans not to usher in a return to those days.

"President Trump last month proposed a six billion dollar cut in funding to the National Institutes of Health," Kimmel said, referring to Trump's draft budget, which was mostly thrown out by Congress.

"And thank God, our Congressmen made a deal last night to not go along with that—they actually increased funding by $2 billion, and I applaud them for doing it. Because more than 40 percent of the people who would have been affected by those cuts to the ... are children," he added.

Kimmel went on to explain exactly what the stakes are in the Republican drive to repeal and replace Obamacare. The current iteration of the plan would significantly roll back protections for pre-existing conditions, allowing states to opt out, and instead set up high-risk pools. But this has been proven to be ineffective and expensive, which is why Obamacare did away with it.

"Before 2014, if you were born with congenital heart disease like my son was, there was a good chance you’d never be able to get health insurance because you had a pre-existing condition," Kimmel explained.

"And if your parents didn’t have medical insurance, you might not live long enough to even get denied because of a pre-existing condition."

Kimmel's story had a happy ending, but the fate of the millions covered by the Affordable Care Act remains to be seen. Republicans are attempting to get the newest version out for a vote, but despite opposition from their own party's more moderate members, they're getting close to having the votes needed to pass it.

To Kimmel, health care isn't a party issue, but a human one.

"If your baby is going to die and it doesn’t have to, it shouldn’t matter how much money you make," he said, fighting back tears. "I think that’s something that whether you’re a Republican or a Democrat or something else, we all agree on that, right?"

Check out the Kimmel's full monologue in the clip below.