"No poo" sounds like a swimming pool rule, but to some it also means washing hair with baking soda and vinegar instead of shampoo.

Tiffany Burke, 31, says she might try it soon, with a goal of becoming as natural and organic as possible.

"I'm, like, 60% there," she says about her use of organic products. "I would say I'm in the middle, because there are still lots of moms who just don't care."

Burke is pregnant and due in November. But the twins she is carrying aren't her biological or legal children.

As a surrogate mother, she's carrying fetuses formed by her brother's sperm and her sister-in-law's egg.

CNN's "Sanjay Gupta, MD" is profiling the legal and emotional issues surrounding Burke's surogate pregnancy.

Burke's interest in natural and organic products began when she was expecting her first child and read the best-selling pregnancy book "What To Expect When You're Expecting."

Some passages suggest that chemicals and pesticides in our food and cosmetics, although legal, may nonetheless be causing harm.

Burke wanted to know more.

"I would just Google and hope for the best. I'd just keep going and going until I saw enough evidence that to me said, just avoid it. Just don't put that in your body," she says.

Eight years later, how she chooses what to buy is a far cry from how she was raised, Burke says.

When sister-in-law Natalie Lucich had to have her uterus removed because a complication with her last pregnancy led to uncontrolled bleeding, Burke offered to carry her next child.

Lucich was overjoyed.

Now, Lucich relies on Burke to make all the right choices for her baby.

"She is organic, and she does know everything that's going into her body. She reads labels," says Lucich. "You never know when you're hiring some surrogate to do it, what they're doing to their bodies."

The FDA says common chemicals like BPA, phthalates and pesticides are safe, but research shows they pass from mother to child, and may be neurotoxins in the womb.

So Burke is like her own regulatory agency, learning as much as possible about the safety of every product on the shelf. She says she doesn't want to take any risks.

Artificial food colorings linked to ADHD in children have been banned from Burke's home. She stores food in glass containers, not plastic.

Even though she might experiment with making her own shampoo, she's passionate about the natural products already on store shelves.

Burke brushes with Tom's of Maine toothpaste, she does laundry with Seventh Generation detergent and she loves "Organic wear" makeup by Physicians Formula.

Ken Cook, president of the Environmental Working Group, says Burke is smart to be proactive.

"We've come to understand that if you take some reasonable steps you can dramatically reduce your exposure to a lot of different chemicals," says Cook.

"If you're going to wait for the government to take action, you could be in store for a lot of exposure."

With the joy of surrogacy comes the burden of responsibility for Burke.

If anything goes wrong with her pregnancy, she says she couldn't help asking herself, "What did I do?"