There are now many for-profit websites where breast milk is sold on the open market, taking advantage of studies that show the benefits of mother's natural milk.
But doctors warn that there is little screening, and there are contamination risks. Breast milk can transmit the herpes virus and even HIV.
Women who sell their breast milk say there is no doubt parents who purchase someone else's milk for their babies need to be cautious.
The Food and Drug Administration does not recommend buying breast milk on the open market, but instead through approved milk banks.
California is one of several states that have certified breast milk banks that do screen the milk.