By Jacque Wilson, CNN

(CNN) – Kim Shifren came home from school one day to find her world turned upside down. Her mom had suffered a massive heart attack; doctors said she would need weeks to recover.

In a matter of minutes, the 14-year-old went from child to child caregiver.

Shifren spent the next month bathing, dressing and feeding her mom before school. When she got home, she cleaned the house and made dinner. Her dad helped when he could, but he worked long hours to support the family.

Two years later, Shifren had to do it all again when her mom had another heart attack. And then again when a third heart attack hit two years after that.

In between, Shifren tried to be a normal teen. But the time she spent living in fear of losing her mom had a lasting impact.

“I felt that getting married and having kids just wouldn’t be right, because I was so sure I would have early heart disease like my mom,” said Shifren, now an associate professor of psychology at Towson University. “I didn’t want to put a husband and children through that experience.”

It’s difficult to say how many child caregivers there are in the United States. The only national survey on the topic, a 2005 report by the National Alliance for Caregiving (PDF), estimated that there were at least 1.3 million between the ages of 8 and 18 – most caring for a parent or grandparent, some looking after a sibling.

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