Lucich looked at her. "I thought you didn't want any more children, you were done being pregnant."

"Yes," Burke responded, "we don't want any more natural children of our own ... but I have this perfectly good uterus!"

They hugged and cried and cracked jokes about Burke carrying her brother's baby.

But by the end of the visit, the sisters-in-law decided to talk with their husbands. What did they think about Burke helping Lucich become a mom again?

For weeks, both couples weighed the pros and the cons. Could Natalie and James afford it? It would cost them about $35,000.

Were there any health risks to Burke? After all, as they knew from Lucich's experience, pregnancy isn't without risk.

Finally, what about the emotional toll? "I remember thinking, what if I didn't want to give up the baby?" Burke said.

Four months later, all of them were ready to move forward. Burke would help James and Natalie expand their family.

Taking the next step

Experts say gestational surrogacy is growing slowly and steadily. According to the Society for Assisted Reproductive Technologies, 1,448 babies were reported conceived via gestational surrogacy in 2010 and carried to full term. There are no statistics on relationships between carriers and the intended parents.

Burke and Lucich contacted Seattle Reproductive Medicine, a medical practice that specializes in fertility issues.

Even though they were family, both couples had to hire attorneys and negotiate a contract that address a wide range of questions, from who would pay for Burke's doctors visits (the Luciches) to the legal process for James and Natalie to take custody of the child. In Washington state, it is illegal to pay for a surrogate's services.

Both couples also had to undergo a psychological evaluation to make sure they were prepared emotionally to go through the process. It took eight months from the time they decided to do it until the first embryos were implanted.

Finally, in January, Natalie's eggs were mixed with James' sperm. Then two embryos were implanted in Burke. That round didn't take. The next one did. Both couples were elated.

"I could not be more honored or more excited to be able to carry their child," Burke wrote in the family's blog. "I have also found new strength and support from my amazing husband, Sean. I know I could not do this without him. My love for him grows more and more each day."

Surrogate mom strives for organic livinga

Then in April, a surprise.

"When the nurse first started the scan, she knew right away there were two sacs. We were able to see the little heart beats of each one and we were all instantly crying," Burke wrote on the blog. An ultrasound showed that she was carrying two boys.

"They always say God has a greater plan than you could ever imagine ... well, He has far surpassed that. James and I couldn't be happier," Lucich added.

It was around the same time that some unexpected realities set in. Burke started getting sick and was exhausted all the time. That made it hard for her to work. It also meant the majority of the housework, cooking and child care ended up falling to Sean, an aspiring filmmaker.

Sean Burke is quick to point out that the Luciches and others help as they can but admits it's still difficult.

"It's been hard; I've been quite stressed out through this process," Sean Burke said. It's also been a strain on his budding career. "My career is just starting to kick off, and I've had to slow down a bit on that, and that's been tough."

Burke also feels guilty that she's missing this time with her boys. Her 7-year-old son, Holland, has especially been affected.

"I think sometimes that I want to help her a little bit. ... I just don't want her to be sick, really," he said.

Recently, things have been turning around. Burke has begun feeling better. She isn't getting sick as much.