Isso será explicado durante a terceira temporada.
Spoilers de Temporada 3, Episódio 9 :
Mr Gold doesn't procure the baby, only the information of it. It is Regina who leaves Storybrooke (she is able to as it is her curse) to meet with the adoption agency. It is not clear how Mr Gold got the information, but it is entirely possible that he did so without leaving town.