You could continue breast feeding if you wanted, but when we received Paige's diagnosis, about 2 weeks prior, the stress from it caused my milk supply to almost stop entirely. We were already having trouble Breast feeding anyways, and having to supplement with formula, so I just decided it would be easier to switch to formula completely.
I had no worries though, because we were battling malabsorbtion, and with the way Enfamil is manufactured, I knew it would be as close to my milk as she could get...if that makes sense...plus, I knew if she was receiving the study formula, she would gain the weight she needed, back.