The number three has held prestige in many fairy tales not only because it holds symbolic importance, but also because it identifies with the Rule of Three, one of the oldest and most influential writing techniques. It represents the Trinity, as well as the concept of mortality.
Birth, life and death represent mortality. The number three is attributed to the body, mind and soul, as well as the triad of father, mother and child. In writing, the Rule of Three states that events should follow a pattern, such as the establishment of conflict, building of conflict and resolving of conflict. This pattern is noticeable in "The Three Little Pigs," along with many other fairy tales.