When Andrea Riley thinks about the women who donated breast milk for her 17-month-old son, Liam, she gets a little emotional.

"It was a really lovely gift," said Riley, 35, who used donated milk from the time Liam was two weeks old until his first birthday. During that time, she received donations from 10 or 11 women.

"Sometimes (breast milk) was delivered to my front door, especially in those early postpartum stages when it was really hard to get out of the house," Riley said. The donations were "always free, which was amazing because there's no way financially we could have afforded the prices we see for breast milk online."

Besides the cost — on average, $1.50 an ounce or $37.50 a day for a healthy baby — breast milk sold online has another major drawback: it could be contaminated.

Those were the findings from a recent study published in Pediatrics. Researchers determined that from 101 samples of breast milk purchased online, three out of four were contaminated with harmful bacteria like strep, staph and, in three cases, salmonella. The study has created a stir online, from major media to "mommy blogs."

Seventy-four percent of the samples would have failed milk bank criteria. Milk banks, operated through hospitals, provide costly breast milk to the neediest babies by prescription only.

Such alarming statistics sent the internet into a tizzy. In the New York Times, Dr. Richard A. Polin at Columbia University said the study was cause for concern.

"This is a potential cause of disease," Polin told the Times. "Even with a relative, it's probably not a good idea to share."

Many advocates of breastfeeding take vocal exception to that analysis, pointing to holes in the study and the difference between online sales and local exchanges.

"The study isn't proving that you should never use donated milk," wrote Maria Guido on Mommyish, in an article titled "Most Obvious Study Ever Says Buying Breast Milk Online May Not Be Such A Great Idea."

"It's proving that you should never use donated milk, that hasn't been screened, from a source that you don't know," Guide wrote. "Shouldn't that be common sense? Apparently, it's not."

Locally, breastfeeding proponents like Laurel Franczek at the Mother's Milk Alliance in Madison worry the study will have a chilling effect on milk sharing.

"We've already gotten quite a few calls," said Franczek, who keeps a freezer of some 1,500 ounces of breast milk in her Madison home.

"Families pursue milk sharing because they know the risks of formula and they feel milk-sharing has less risk," she said. "There's no such thing as a completely safe way to feed your baby. (But) there are less risky behaviors."

Dr. Anne Eglash, a family practitioner in Mt. Horeb, is an authoritative voice on breastfeeding. Eglash heads UW Health's lactation services, helped organize the Breastfeeding Coalition of South Central Wisconsin, co-founded the Academy of Breastfeeding Medicine and serves on the board of directors for the Mother's Milk Bank of the Western Great Lakes.

"Yes, there's bacteria in breast milk," Eglash said. "Breast milk is not a sterile bodily fluid. We don't ask moms to test before they feed their babies.

"But when you're buying this kind of milk, it's already expressed; you don't know how long it's been sitting out. It creates more of a risk of infection for the recipient child."

Babies who get harmful bacteria directly from their mothers are also receiving antibodies to fight it, Eglash said — antibodies that may die during shipping and storage of breast milk. Some samples in the study were shipped improperly, which can allow bacteria time to proliferate.

Also, Eglash noted, the study may have weeded out the most conscientious donors. Researchers requested just four to eight ounces of milk from each seller. That amount could seem suspicious to moms, who then assume it's going to a male fetishist or an athlete wanting to bulk up instead of a hungry baby.

According to a story on The Verge, 57 women were dropped from the study because "they wanted to communicate verbally or inquired about an infant."

"Women who donate to milk banks ... they're marvelous people," Eglash said. "They want the milk to go to someone who really needs it. They're looking to do the right thing and not waste their breast milk."

The connection between moms is one of the side benefits of the Mother's Milk Alliance (MMA), a Madison-based milk-swapping service that Eglash says is "unique" and "very altruistic." The organization, founded in 2007, is applying for nonprofit status.

Using donations from recipients, the MMA tests all donors for infection and communicable diseases before releasing their milk. 

Franczek, who has worked with MMA for two-and-a-half years, said she's never heard of any problem or illness caused by donated milk from the alliance.

"We screen the donors. We counsel them in milk collection," Franczek said. "We're all health professionals either in the home-birthing community, or work with breastfeeding counseling. We saw this need ... for more information, for increased safety. We wanted families to feel better about milk sharing."

The best way to make sure milk is safe, advocates agree, is to know and trust the donor.

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For an unpublished study, Eglash polled 400 lactation consultants and pro-breastfeeding doctors and nurses and more than 95 percent of them felt milk sharing was appropriate.

"The message I would give to mothers is they should not purchase breast milk," Eglash said. "It should be done in a safe way, where testing is done. There was low concern about tainting of milk, putting in dangerous chemicals or medications. The respondents felt the safest situations were sharing among relatives and friends."

That's what Rachel Kiley, 24, did for her 4-month-old daughter Eva.

"If you know someone who's pumping, you can get extra milk from friends you trust," Kiley said. "I got milk first from a friend whose baby was 10 months older. I think knowing people here locally made the sharing process easier."

Of course, despite the "breast is best" mantra from many corners, breastfeeding isn't the only option for babies. Sharon Fandel, 34, went to various specialists to increase her breast milk production after her daughter, Neva, was born.

When the milk didn't come, she and her husband weighed their options.

"We did consider formula," Fandel said. "We felt that donated breast milk was the best path for our family."

Fandel, a conservation biologist who works at the Wisconsin Department of National Resources, understands that nearly everything she does with her child is, on some level, risky.

"Every time I buckle my kid in her car seat there's a risk," Fandel said. "Any time I feed her a new food there's a risk. There would be a risk whether I fed her formula or donated breast milk."

But sharing breast milk, especially when it's done with care, can be a rewarding experience for young families.

"Milk sharing ... is how our species got to where it is," Eglash said. "For 400,000 years, a mother dies, the baby gets picked up and breastfed by another mother. Or the mother doesn't have enough milk and the baby survives because someone else breastfed the baby. That's how our species came to survive.

"It's natural. It's just that in this day and age, we want to do it safely."

Since 2008, Lindsay Christians has been writing about fine arts and food for The Capital Times. She loves eating at the bar, going to the theater, fine wine and good stories. She lives on the east side with her husband, two cats and too many cookbooks.