From PEOPLE Magazine Click to enlarge
She may stand no taller than the average 3-year-old, but Jennifer Arnold's ambitions have always been supersized. "I was a very focused child," says Jen, who is 3'2". "I wanted to be a doctor. And I always dreamed—hoped—I'd fall in love and get married."

So far Jen is batting a thousand. As one half of The Little Couple, a hit reality show on the TLC network, she's got the career (as a successful neonatologist) and the guy (her husband of two years, business owner Bill Klein). "Jen really doesn't let anybody say, 'You can't do it,'" says Bill, 35, who is 4 ft. tall and has a similar type of skeletal dysplasia—a bone-growth disorder that causes dwarfism—as his wife. "She's incredibly strong. As soon as I met her, I knew. I was done. There's nothing fake about her." More than a million viewers are similarly smitten, tuning in each week to watch the couple deal with life in a larger world. (A third season begins in June.)

But the next chapter of their story will be challenging. "I've had more of those days lately where I think, 'I want to have a baby,'" says Florida-born Jen, also 35, who treats critically ill infants at Texas Children's Hospital and is also an assistant professor at Baylor College of Medicine. "I'm not getting any younger. That clock's ticking."

But because of challenges posed by Jen's tiny frame (she buys clothing at kids' stores) and her extremely short airway, which would make it difficult to intubate her if she had to undergo anesthesia, it would be "a very high-risk pregnancy," says Dr. Judy Rossiter of St. Joseph Medical Center near Baltimore, whom Jen consulted. That was enough for Bill to hear: "She's more willing to put herself in danger," says the New York native. "But I'd jump in front of a car to make sure she's okay. I need her around."

So Jen and Bill have decided to explore surrogacy, though finding someone to carry their child is not going to be easy. One concern is the cost (which can run upward of $80,000). Even more daunting is the fact that should a fetus inherit both Jen and Bill's dominant dwarfism genes, a baby would have little chance of survival. Now the couple is hoping that genetic testing will be able to rule out the lethal gene combination in an embryo before implantation in a surrogate. "It's hard to put someone through that and then have the baby not survive," Jen says.

The couple, who connected on a dating Web site ("I e-mailed him, and my pickup line was, 'Hey, have we met at a [little people's] convention before?'" laughs Jen), are used to making adjustments. At home Bill cooks from atop a step stool; Jen drives an SUV rigged with pedal extenders. They're also prepared to get creative when it comes to adding to their brood; they're researching adoption—particularly of babies with dwarfism—if surrogacy doesn't work out. Either way, as they oversee construction on a new, customized home near Houston—"No more climbing to get stuff off the shelves!" marvels Jen—they are saving space for a nursery. "We're both kind of science and math geeks, so we're working on it logically," says Bill. "But we're open to whatever makes us a family."