2 days if not frozen
The refrigerator section temperature varies because people open the doors to move foods & drinks in and out all day long.
If breastmilk is meant to be used, it can go in the fridge section but should be used within 1-2 days. If breastmilk is meant to be frozen, it should be put in the freezer as soon as possible after pumping. Store up to 3 months in a fridge freezer or 6 months in a deep freezer.