Michelle & Jim Bob Duggar On Josie: "It's A Miracle She's Doing So Well"

Seven weeks after their 19th child made her very early arrival, parents Jim Bob and Michelle Duggar are relieved to report that little Josie is doing well - but admit that there is still a long road ahead.

"It's a miracle she's doing so well," Jim Bob tells People. "Years ago, a baby this small wouldn't have lived an hour."

Born 15 weeks early due to Michelle's pre-eclampsia, Josie weighed just 1lb 6 oz. Her parents reveal that she is now up to 2lbs, 3 oz and is taking breast milk through a feeding tube.

Expressing gratitude to the hospital staff who have been caring for Josie, Michelle, 43, says, "It is incredible what the doctors and nurses can do to save the life of this little person."

Still, Jim Bob acknowledges that she isn't out of the woods just yet.

"Doctors tell us, 'never trust a preemie,' because you can't know what is going to happen," he says. "It is a very day-to-day thing. It is the hardest thing we've ever been through."

Adds Michelle, "We don't know if there is going to be another big hill to go up. We are grateful for the wonderful days when she has been good. We know at any moment, things could change."

Josie's birth will be featured in 19 Kids and Counting: Special Duggar Delivery, set to air on TLC on January 31.