[Please note that the rules have changed since this post was written. See the comments for updated information!]
A mother who travels without her baby and needs to pump may be confused by the latest changes in airline restrictions on what can be packed in carry-on luggage. Andi Silverman of Mama Knows Breast examined what the rules are for taking expressed breast milk on an airplane. Basically, if you are traveling with your baby, you can carry on pumped breast milk (or formula) and ice to keep it cold. If you are traveling without your baby, you are limited to one quart-sized clear plastic zip-top bag holding three-ounce containers of breast milk. Any additional milk must be transported in your checked luggage or shipped home separately. Read Andi’s article here for a detailed explanation.