She says doctors told her, "If we conceived (again) on our own, we would have a 50 percent chance of having another child with Fragile X Syndrome."
So, reports Early Show Consumer Correspondent Susan Koeppen, Karen and Mark turned to egg donation as a solution. And six months ago, Karen gave birth to their second son, Eric.
"I am so happy that he's here," Karen glowed. "And, if it weren't for the donors, this could not have happened for us."
"What do you say to a donor?" she added. "It's an invaluable gift that you've given to someone. You have healed a person. You've possibly healed a marriage. You've healed someone's soul. You've filled a void for somebody."
"You can't thank them enough, honestly," Mark concurred. "And we're just so grateful."
To find a donor, they turned to the Center for Egg Options, outside Chicago.
The Center's Nancy Block told Koeppen it's seen "probably at least a 40 percent increase in the number of people who are donating eggs," and she "absolutely" thinks it's due to people looking for money in the poor economy.
No only is the center seeing more donors, but repeat donors as well, Koeppen points out.
Women can earn $7,000 or more for just one donation.
"That's a lot of money," Block says. "It's great for school. It's great for the mortgage. It's great... great to help their families out. And you know, it's... it's something that they feel good about."
But, Koeppen notes, egg donation isn't an easy way to make a quick buck. It's a time consuming medical procedure, with risks. Donors will spend weeks taking fertility drugs. Medications can cause hot flashes, headaches and vision problems. Donors also have to have frequent blood tests and ultrasounds. And it takes several days to recover after the eggs are harvested.
But Christy Bush helps support her two kids and pays for nursing school with the money she's earned donating eggs -- nearly $30,000.
Over the past four years, she says, she's donated four times and, with money being tight, she's decided to donate again.
"It makes it so that I'm not working 40 hours a week. ... It's given me hope that I can actually do the parenting and the schooling and still be home and doing great things and actually watching my kids being be raised," Bush says.
Parents such as Karen and Mark call it a win-win for everyone.
Egg donors must be a certain age, usually 21-to-34.. And women are allowed to donate only a few times. The limit is usually about 6. Egg donation has been around since the '80s.