"I'd never thought about what my plans (to have children) were," she says. "I'd been raised with my mom's mind-set when she took me home that I was a child, not a china doll. I wasn't a sick kid, and I was raised like any other child, so I never thought about it, although I had more doctor appointments. I had no idea I'd have to be careful with pregnancy."

Children born to women who had congenital heart defects are also slightly more likely to have their own heart defects, although not necessarily the same ones. If the congenital heart defect is part of a chromosomal syndrome (and it's usually not), the chance a child will have a defect increases even more.

Melissa Spaulding, 26, was born with mitral valve regurgitation. She had her first open-heart surgery at age 5. As a teen, her mom told her if she got pregnant, she'd need extra monitoring — information that was crucial when she was carrying Devan, now 3.

She had an echocardiogram during the pregnancy, along with other tests. She regularly made the trip from Riverton, Wyo., to the U. to see her high-risk obstetrician and her cardiologist, and she didn't have any problems. But partway through her second pregnancy — Trevor is now 6 months old — regurgitation increased, enlarging her heart's upper-left chamber.

Still, she was able to work until she was 32 weeks along, and then she came to Salt Lake City for the rest of her pregnancy. When they reached the 36-week milestone, Trevor was born by emergency C-section after her blood pressure skyrocketed. She was in the hospital for a week, including a short stay in intensive care.

Two months later, she had another heart surgery. Although she's exhausted, she's recovering well.

Alyssa had no problems during her first pregnancy, either, although she was watched more closely. "I had more tests and more ultrasounds and in a way that was kind of fun for me. I got to see my baby more and hear the heartbeat more," she says of her daughter, who is now 4.

"I thought that went pretty smoothly," she told her doctors later, when she was considering a second pregnancy. "Can I do this again?" They assured her it would be fine, but midway through the pregnancy, she began to have arrhythmias — irregular heartbeats. It was not clear, though, whether pregnancy kicked it off since people born with transposition of the great vessels at some point do usually develop rhythm abnormalities. "They know all these things will happen, but not when," says Alyssa. "'She'll need a pacemaker.' Check. I've got that. 'She'll have arrhythmias.' Check again."

Echocardiograms showed in both her pregnancies that there are no problems with her babies' hearts.