Puberty. Usually, xy babies are born looking like healthy baby girls. During puberty, however, they don't develop secondary sexual characteristics that require testosterone such as axillary or pubic hair. Since estrogen is present, they grow breasts and develop a thin waist with larger hips, but don't have periods since they lack a uterus. Most often, lack of periods by age 15 or 16 leads to the diagnosis.
It Depends. Most cases of incomplete ais are diagnosed in childhood since they exhibit both male and female sex characteristics most cases of complete ais are diagnosed during puberty or later androgen insensitivity syndrome (ais) is when a person who is genetically male (who has one x and one y chromosome) is resistant to male hormones (called androgens).