Research has shown that a combination of pumping and hand expression can help establish and maintain breast milk supply for mothers of premature infants.

http://www.hygeiababy.com/news-details.php?nid=9

I wish I had known this when I decided to exclusively pump for my son. It took a month for me to establish my supply to meet my LO's demand. The nurses and lactation consultant never mentioned anything about hand expression. I didn't learn about it in my breastfeeding class either. 6 months later, and I primarily use my pump. On occasion I will hand express after a pump session to get rid of a minor clogged duct.

Were you educated about hand expression by your nurses or lactation consultant? Have you tried it to establish and maintain your supply?