Scholars suggest that marriage rites are an extension of menarchal rites, which may explain why many bridal dresses were historically red. The bride would also walk on a red carpet to the wedding ceremony, wearing a red veil.*
Why do you think white has replaced red as the dominant color for most wedding dresses?
*Source: Grahn, Judy. 1993. Blood, Bread, and Roses: How Menstruation Created the World. Boston MA: Beacon Press.