When a photo of Pennsylvania mom Jessica Colletti breastfeeding her toddler and her friend’s toddler at the same time took the Internet by storm this past week, it laid bare (ahem) the growing trend of sharing breast milk. 

Research in a 2014 issue of Breastfeeding Medicine confirms that donations, sales and informal sharing of breast milk are all on the rise. Some 13,000 posts or ads for breast milk crop up online each year, according to the researchers’ estimates, and there are literally hundreds of milk sharing groups on Facebook and Twitter. 

“Mothers are increasingly aware that formula doesn’t come close to having the nutritional and immunological properties of their own milk,” explains lactation consultant Diana West, of La Leche League International. “And if they don't make enough milk for any number of reasons, they’re realizing that other mothers in their communities and beyond are willing to share their extra milk to help other babies.” Some women decide to use donated (or purchased) "liquid gold” when they adopt an infant instead of turning to formula.  

It’s well accepted in the medical community that breast milk offers an ideal nutrition package. “Benefits include reduced risk of allergies and illness for baby for starters,” says pediatrician Ari Brown, MD, FAAP, a spokesperson for the American Academy of Pediatrics (AAP) and author of ”Expecting 411,” “Baby 411” and “Toddler 411.” The AAP recommends breastfeeding babies exclusively for the first six months and then continuing throughout the first year of life.

But before you feed your baby milk from another mother — be it a complete stranger or your oldest friend — here’s what you need to know.

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1. Breast milk is a living food. That’s a polite way to say that it’s a bodily fluid, like blood, so the risks are similar to receiving a blood transfusion. “You would want to know that blood was free of germs, like HIV, right? And that it was not contaminated or spoiled?” Brown says. She recommends getting breast milk only from certified milk banks, which screen donors for diseases and also pasteurize the milk, lowering the odds of any contamination. To find a certified milk bank near you or for info on donating, contact The Human Milk Banking Association of North America.

2. You’ll need a prescription. Babies with medical needs get first dibs on the milk at certified milk banks, so if you have a full-term healthy baby, you can’t simply walk into a milk bank, open your wallet and walk out with milk. Which is why many moms who can’t get an Rx turn to nonprofit networks such as milkshare.com. Both the Centers for Disease Control and Prevention and the Food and Drug Administration advise against milk sharing because of the potential for disease transmission, but at this point there’s no data showing donor milk has made babies sick. West emphasizes that it’s important to pasteurize any donated milk to inactivate pathogens that could transmit disease. (Here’s how to do that.)

3. Breast milk changes over time according to your baby’s age and stage of life. So if the mom of a 12-month-old shares her milk with your three-month-old, your infant may not get all the nutritional components she needs. You can work around this by seeking out milk from a mom nursing a child whose birthdate is a close match to your child’s.

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4. Breast milk is pricy. Well, it’s free for you to produce it, but if you want to buy bags from a certified milk bank, expect to pay $3 to $5 an ounce, with only some portion possibly covered by your insurance, depending on your baby’s health and your plan. “It is certainly not cost effective for non-premature babies when formula is an acceptable alternative,” Brown says.

5. Buying online is risky. Although there are more and more opportunities to buy breast milk on the Internet, it can be dangerous, especially for babies with medical conditions. In a study published in the journal Pediatrics in April, researchers found that 10 percent of samples of human breast milk bought on the Web contained added cow’s milk and others were topped off with infant formula, posing a risk of infectious disease from bacterial and viral contamination. Prior research found that more than 75 percent of milk samples purchased online showed signs of bacterial or viral contamination.

6. Community sharing is not a sure bet. Moms who donate their extra breast milk — via websites such as Eats on Feets, Human Milk 4 Human Babies and Only the Breast — have nothing to gain by diluting their milk, unlike people who sell breast milk for profit. So it’s likely to be pure. But is it safe? “Even if it is your best friend or sister who is donating the milk, you still don't know if it is germ-free unless you ask her to get HIV and Hepatitis B tested prior to accepting the offer,” Brown says. And with anonymous donors, you don’t know about their lifestyle choices — are they smokers or drug users? Meeting and chatting with a local donor mom in person can allay some of these fears, but you’ll still want to know if they’ve been screened for a variety of transmittable diseases and viruses, including HIV, hepatitis, herpes, syphilis, tuberculosis, cytomegalovirus, strep and staph.

Still, thousands of moms across the country are finding breast milk for their babies, and the World Health Organization (WHO)/UNICEF supports that initiative. In its publication, “Global Strategy for Infant and Young Child Feeding,” the WHO recommends milk sharing via a healthy wet nurse or a human milk bank for babies who can’t be breastfed or can’t get expressed breast milk from their own mother. Formula, according to WHO, is a last resort.

“It's wonderful when mothers help each other, and it’s great for more babies to have human milk,” West says. Brown adds, “It is truly giving a gift to those in need.”

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