Labial adhesions occur when the folds of the skin of the vagina (labia) stick together. This closure may be partial (either upper or lower labia) or complete. The adhesions normally occur in pre-pubertal girls. The cause of closure is often from vaginal irritation that when healing occurred, adhesions formed.
The possible causes of irritation are from stool (wiping form back to front), bubble baths or something unknown.