First Lady Michelle Obama joined her husband Wednesday in advocacating for his health reform law for a “Meeting with Moms” to talk about the Affordable Care Act.

But in an interview with Rev. Al Sharpton set to air on his radio show Thursday, she revealed one of the most frightening experiences she had as a mother– describing how her daughter Sasha once got meningitis – to help illustrate why she believes the health reform law is so important.

“I will never forget. It was a day when, you know, one hour she was fine, she was normal, she was happy, doing everything I was used to her doing and the next hour she was crying inconsolably, and that just wasn’t like her. And I did everything,” she said. “I tried to do – tried to feed her, tried to rock her, tried to burp her. Finally, I just thought, I need to call my pediatrician.”

“We had health insurance, which meant I had a really good relationship with our pediatrician. So he knew me, and he knew I wasn’t the kind of mother to call up just because my baby was crying,” she continued, adding that after she described the baby’s symptoms, he insisted they rush to the emergency room.

“As it turned out, she had meningitis. And they had to do a spinal tap. She turned out – obviously, as this story ends, she is fine, she’s healthy, she’s a beautiful young lady, but if we hadn’t had insurance, and access to a pediatrician, and access to a hospital where we didn’t have to worry about the cost of care… If we had waited overnight, if we had postponed acting, there’s no telling what the outcome would’ve been,” she said. “And that’s why for me as a mother, I am just – you know, I just can’t put into words how important it is for every American, for every mother, for every person in this country to have health care, because you just never know what kind of curveballs life is going to throw you.”

It’s not the first time the Obama family has talked about Sasha’s illness. The topic came up during the 2012 campaign when the president dined with supporters. “Your world narrows to this very small point,” he said of the experience. “There’s one thing you care about, you don’t care about anything else.”

The first lady explained why she believes mothers are the most important group to talk to about this issue.

“Mothers are the ones who make the decisions about health care in their families,” she said. “They’re the ones dealing with sickness on a regular basis. They’re the ones who have the ear to their kids, their teenagers, their young adults who think they’re invincible and don’t need insurance. We’re talking to them because they’re the ones with the stories just like me.”

“I want people to have the peace of mind that I have,” she said, “because it’s hard enough being a mother, trying to raise kids and then worrying about whether, if they get sick whether you can help them. There is nothing more powerless than being a mother who can’t help their child when they’re sick. That’s just to me untenable.”