Why am i producing less breast milk when i pump?

Stress, dehydration: Not drinking enough fluids and stress and common reasons for decreasing milk supply. Also, if you are substituting pumping for nursing, pumps are not as good as your baby at stimulating the supply. Don't give up though! resting and drinking plenty of fluids will help and you can also try looking at a picture of your baby while pumping.

Maybe: Remember that pumping gets milk out with a different mechanism than real feeding. For many women that means less expression of milk. For many women, milk pumping is also painful and thus do it less than maximally. If pumping, relax (relaxed moms pump more milk), pump often, hydrate, don't smoke (which may decrease supply) and stay heathly. All those things increase pumping success!