Pump and dump is a term that refers to a technique used during lactation.
What is it?
Pump and dump refers to using a breast pump to express breast milk and then disposing of the milk usually by dumping it down the drain.
Why would you want to go and do a thing like that?
Frequently, this is done when the nursing mother is on medication that the baby shouldn't have or if she is away from the baby for an extended period of time yet wants to maintain her milk supply.
There is quite a bit of disagreement, most likely due to unknowledgeable doctors, over when a woman really needs to pump and dump due to medication. Some doctors will indicate that almost any time a woman is on medication, she should pump and dump, while others will indicate that the only time a woman should pump and dump is if the medication has been proven to be hazardous to infants, such as chemotherapy drugs.
Frequently, after pumping exclusively for a significant amount of time, women will start to notice a decrease in their milk supply. Pumping and dumping certainly has its purpose, but it's almost always better to nurse an infant directly if possible.