I started donating again when each of my baby's were about 5 months old. With my son, I didn't notice any drop in supply. I drank a lot and made sure I went to bed early that night. However, with my daughter, I have been struggling since around month four with my supply. It has been very frustrating as I didn't have any problems with my son and even had a three month freezer stash going. So, when I I gave blood this last time (daughter just turned seven months), my supply crashed that evening. It was better the next day, but losing the fluids really effected my production.