i have pumped extra milk almost daily since esther was born. the main reason for this is because we hope to adopt a baby (though we thought it would have already happened by now) and i wanted to keep my milk supply up so that we can give him/her breast milk, as well as have a stockpile in the freezer of extra milk so that we will have extra cushion to aid with the transition when s/he comes.
to be honest, pumping is a sacrifice, and its not my favorite thing in the world. that being said, there are many reasons i am really glad that i have done it, completely apart from being able to give our next baby the best milk.
in case of emergency. if you were to have an emergency surgery (such as an appendectomy) or have to be on certain kinds of medicine for a time, you wouldn't be able to give your milk to your baby for a time (what lots of people call "pump and dump". the thought of dumping liquid gold is heartbreaking... but i digress...). if you have a stockpile of extra milk in your freezer, you baby wouldn't have to adjust to a different kind of milk during this time (which can really mess with their digestive systems).
this was especially in my mind recently when i had a kidney infection and had to go on really strong antibiotics. fortunately i was still able to breast feed during this time, but it was easy to imagine having to find an alternate way to feed esther if i had been prescribed a non-BFing friendly med.
to give away. there are so many babies who could benefit from your extra milk! i was thankful to get several donations of breast milk for our first foster baby girl. in addition to giving to adopted/fostered babies, you can donate to milk banks, which give the milk to premature babies who's mothers cannot (or choose not to) produce breast milk. lastly, you can give milk directly to mothers who can't (for whatever reason) produce enough for their own babies. i have had the honor to give extra milk to three different mamas i know.
since i have also been on the receiving end of breast milk, i can tell you that there is no better gift than to give breast milk to a mama who wants to give her baby "liquid gold".
to keep your milk supply up. i notice big changes in my milk supply at different times, relating to hormone changes (ovulation, etc), stress, and dietary changes. thankfully, if my milk supply is low, esther still gets enough to eat, but i just can't pump as much during those times (say, 1-2 oz per day instead of my usual 4-6). pumping helps me to have extra cushion in my supply, which gives me comfort to know i will always have enough for her.
similarly, if you have a stockpile in the freezer, you can always supplement with this stockpile if your supply is too low to sustain your baby for a time (for example, some women can't produce enough milk while they are on their period and supplement their babies with extra milk pumped at other times of the month).
do you pump extra milk? what do you do with the extra?