Is it safe to share breastmilk?

On January 6, 2005, the Wall Street Journal published a story on the growing trend of mothers sharing breastmilk, either by selling it or donating it, including offering milk over internet sites such as Craigslist. The Massachusetts Breastfeeding Coalition is offering some suggestions to help mothers make their decision.

The superiority of human milk is well-established, and it is particularly important for premature babies. The American Academy of Pediatrics, the World Health Organization, and the American Academy of Family Physicians all recommend exclusive breastfeeding for the first six months of life, and use of complementary foods, with continued breastfeeding, for a year or beyond. This confirms the need for and importance of breastmilk. Many women who cannot otherwise breastfeed wish their children to have breastmilk and avoid the inadequacies and problems associated with infant formula. Some breastfeeding mothers have an abundance of milk and may be reluctant to throw away their own milk, preferring to see it put to good use.

There are several considerations to sharing breastmilk, however. The most important risks are HIV and the possibility of transmitting maternal medications in milk that can be unsafe for the baby. HIV can be transmitted in mother’s milk, and thus it is recommended that women with known HIV infection in the US should not breastfeed nor share breastmilk. One may not know if source milk may have HIV, and milk at milk banks is routinely pasteurized. HIV is inactivated by heating. There has been research in Africa into using a home pasteurization method known as Pretoria pastuerization, which has been shown to effectively inactivate HIV in breastmilk in one study by Jeffrey et al. Home pastuerization of milk is not routinely done in the US.

There is a theoretical risk of Hepatitis B transmission, but this would occur only if the milk were contaminated by an infected mothers blood (if, for example, she had an abrasion on her nipple). The risk of tuberculosis through shared breastmilk is negligible, unless the mother has a localized tuberculosis infection in the breast itself, which is exceedingly rare. The risk of TB to a nursing infant occurs when an infected mother breathes or coughs infected particles onto an infant, not through her milk.

It is important to know if the donor mother smokes, drinks alcohol, or uses any drugs or medications. It is generally accepted that it is safer for a child to be breastfed by a mother who smokes, than to be formula fed. However, smoking significantly diminishes milk supply and it relatively unlikely that a mother who smokes would have excess milk to donate or sell. Small amounts of alcohol are generally considered safe – less than one drink a day, but alcohol can cause sleeping problems or feeding problems in an infant. Large amounts of caffeine may cause irritability, especially if very young or preterm infants, but one or two cups of coffee a day is generally considered safe. All illegal drugs, such as marijuana and cocaine, are considered unsafe. If there is a strong family of peanut allergy in the babys family, it recommended that the (source) mother refrain from eating peanut products.

Most medications are safe, and the list of unsafe medications in breastfeeding mothers is relatively short. Examples of safe medications include all antibiotics, medications for asthma, thyroid replacement, and most antidepressants. The best reference for determining the safety of drugs in breastmilk is Thomas Hales Medications and Mothers Milk, or the list published by the American Academy of Pediatrics: The Transfer of Drugs and Other Chemicals Into Human Milk — Committee on Drugs 108 (3): 776 — AAP Policy. Of note, milk banks do not generally allow milk from women taking most medications or from women who use tobacco.

Herbal medicines may pose a risk, because their labels may not accurately reflect their true contents, and they may also contain toxic materials. A recent study from the Journal of the American Medical Association (Saper et al) found that 20% of South Asian herbals purchased in the Boston area contained toxic levels of lead, mercury, or arsenic.

Often people ask if there may be environmental toxins in breastmilk that may be unsafe. The risk from mercury is negligible, with dangerous levels only being reached if there is exposure from a mercury spill or ingestion, but not from dental fillings. Another recent study, (Jensen et al), found that even when mothers milk contained methylmercury from ingesting contaminated whalemeat, breastfeeding was still associated with marginally better scores on neurobehavioral tests,

Of note, a toxin may cause harm to the developing fetus child from exposure during pregnancy, and this may be of significantly more consequence to the child than breastmilk exposure. This particular study controlled for the amount of prenatal exposure by measuring methylmercury levels in cord blood.

It is also important to realize that formula may also be subject to contaminants, environmental toxins, and bacterial contamination. Powdered infant formula is not sterile and has been recalled for bacterial contamination on multiple occasions. The cows whose milk provide the basis for making formula are subject to the same environmental toxins as the people who live near them.

Finally, milk from family or friends may not necessarily be safer than milk from someone unknown. As with designated blood donation, family and friends may be reluctant to reveal important personal facts that may put their milk at risk.

In sum, there are risks of sharing breastmilk. Most risks can be minimized by obtaining an accurate history from the donor mother, bearing in mind one can never obtain a history that is completely trustworthy. Unknown HIV infection represents the most serious risk, and while heating breastmilk through an effective home pasteurization process could inactivate HIV, this is not routinely done in the US. Both the American Academy of Pediatrics and La Leche League discourage sharing breastmilk. It is suggested that donor mothers be screened using the protocol developed by the Human Milk Banking Association of North America.

Milk Donations:

Massachusetts Breastfeeding Coalition, March 2005