Hi Angie,
I have a 9 month old daughter and was having the same problem. For a while I even took her clothes off of her to feed her because it was ruining her clothes. The answer is BIZ! I start my washing machine, warm or hot water works best, put the setting on low water level. Let the water start moving put in her clothes and let it agitate for a few minutes. Then I turn the machine off and let them soak. You can decide how long. When I get ready to wash them, I raise the water level (change temp to cold) and add the detergent. I have had some stains that I had to do this twice. But it works. Besure to look at the clothes good before you put them in the dryer. Once they've been in the dryer the stain is pretty much set in.
Good Luck, S.