Re: shipping BM
You can ship it back overnight if you want. Wrap the frozen milk in newspaper, pack in a styrofoam cooler with dry ice. Wrap the cooler in newspaper, and put in a cardboard box. Ship this package.
I've also heard of mothers checking the cooler at the luggage counter. Tape it shut, so it stays shut through the bouncing of the luggage. Consider doublebagging the milk inside the cooler, so if one bag leaks, everything isn't covered in milk. Same thing for the ice - put it in bags. You could also use dry ice here, too. Ship with whatever shipping method is available to you at your location, and where you want it to go.
Icy salt water stays much cooler than just ice water, so think about throwing salt in with your ice.
Some airports are now letting breast milk go through security, some aren't, and will make you throw it away right there at the security checkpoint. So, if you pump some while you're at the airport, go ahead and try to take it on the plane with you. A nice security person may let you through. This seems to be more prevalent at the smaller airports, than the big hubs.
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