Being a mom is full of sweet moments. It’s full of tough moments, too. Kristi Lopez of Fort Worth says she never could’ve expected quite how tough it’d get.

“I didn't know what was going on,” she recalled through tears. “But I was scared for my kids because the way they were acting, I knew something was wrong, but I didn't know what was wrong.”

Just one week after her third child was born, the then 42-year-old rushed to the emergency room after her blood pressure was sky-high. “It was probably early afternoon I felt a pain in my chest,” Lopez said.

The diagnosis shook her: she was having a heart attack. “I'm thinking 50s and up having a heart attack, but not at 42,” she said.

Kristi’s case is part of a troubling trend, exposed recently by NYU medical researchers. “They did a study over the course of 12 years,” said interventional cardiologist Dr. Neeraj Badhey of Texas Health HEB, in which they analyzed about 50 million pregnancies. “And they noticed how many of these women had heart attacks during their pregnancy or three to six months after pregnancy.”

And what they discovered over those years, Dr. Badhey says, was the risk of suffering a heart attack during and right after pregnancy had risen 25 percent. “The most likely theory is women are getting pregnant later in life,” Dr. Badhey said. “The older you are, the higher your risk is.”

Especially during pregnancy. “Your blood volume, your plasma, increases about 40-50 percent so your heart's working that much harder,” he said.

Obesity, high blood pressure and diabetes are also risk factors—not to mention the physiological, hormonal and emotional changes women face during pregnancy. “In this practice, I think we see seven or eight cases a year,” the doctor said.

We asked if he thinks the average pregnant woman knows this is a risk. “I don't think the average pregnant woman knows,” he said.

“I had no idea that was even a thing that could happen,” said Julie Cogdill of Richardson.

Six days after Julie’s second son was born, she was rocked by intense chest pain. “I knew from just my college classes that this was a heart attack,” she said. “This was my heart, this was radiating down my arms, but I was 29!”

She couldn’t believe it was possible. “It must be something different,” Julie thought. It took days before medical experts would confirm she’d had a heart attack at 29. It was a tear in her artery after childbirth.

“As soon as they found it, they were so surprised—everybody in the room was shocked,” Julie said. “They’re like, ‘get the camera, send this to so-and-so.’”

Like Kristi Lopez, Julie is healthy and fully healed. “I have not talked about my story for so long because I know that's a scary thing to think this could happen and it is still rare, but it is happening with more frequency that we should be paying attention,” Julie said.

And that’s the key, Dr. Badhey says: know the risks and listen to your gut. “I think it's just an awareness issue and modify your risk factors,” he said.

“Being pregnant's not scary—it's a beautiful thing,” Kristi said. “Just have faith and trust your body and trust yourself,” echoed Julie.