How often should mom pump?
8-10 times per day: Until supply is well established, it is important to get at least eight good nursing and/or pumping sessions per 24 hours. Ten sessions per day is better, particularly if you have twins or higher order multiples.
These sessions don't need to be evenly spaced, but you should be nursing/pumping at least once during the night in the first few months or anytime you notice a decrease in supply. Avoid going longer than 5-6 hours without pumping during the first few months.
When pumping during the night, milk yield tends to be better if you pump when you naturally wake (to go to the bathroom or because your breasts are uncomfortably full) than if you set an alarm to wake for pumping.
If you are having a hard time getting in enough pumping sessions, adding even a short pumping session (increasing frequency even if milk is not removed thoroughly) is helpful.
How long should mom pump at each pumping session?
If baby does not nurse at all:
The first few days, before mom's milk comes in, hand expression is often the most effective way to express colostrum. Double pump for 10-15 minutes per session for additional stimulation.
Once mom's milk is in, pump for 30 minutes per session, or for 2-5 minutes after the last drops of milk.
If baby nurses but does not soften the breast well
Double pump for 10-15 minutes after nursing.
Empty the breast as thoroughly as possible at each session. To ensure that the pump removes an optimum amount of milk from the breast, keep pumping for 2-5 minutes after the last drops of milk. Use breast massage prior to pumping, and massage and compressions during pumping to better empty the breasts and increase pumping output.
Additional tips
Rest & relax as much as possible.
Skin-to-skin (Kangaroo care) can make a significant difference in pumping output.
If double pumping is difficult to coordinate in the beginning, then single pump, alternating sides. Move to double pumping as soon as you can.
Avoid any medications that might interfere with milk supply (hormonal birth control, pseudoephedrine, ethanol/alcoholic beverages, bromocriptine, ergotamine, cabergoline)
If supply is not increasing as expected by 7-10 days after birth, consider the use of galactagogues. Fenugreek, metoclopramide (Reglan) or domperidone (Motilium) can be helpful for increasing milk supply.