If you're looking for your birth mother as an adoptee, you have a few search options available to you after you're a legal adult. There are also other ways to go about looking for a birth mother.
One way to search, although it is a passive form of searching, is to find and register with one's state registry. The way these registries work is by mutual consent. If a birth mother and an adoptee both register, thereby giving their consent, to the release of the sealed adoption record, both parties will be notified. When an adoption record is unsealed, the adoptee will be able to access identifying information about his or her birth mother and, possibly, father.
More active ways of looking for a birth mother include turning to online databases, where people can independently register themselves and look through other registrants' profiles. Adoptees can also hire Search Angels, which is the title of volunteers who help connect adoptees looking for their birth mother, father, sibling or relative.
Hiring a private investigator is also an option as is petitioning the courts to allow a confidential intermediary to access an adoption record and facilitate communication between an adoptee and birth mother.
International adoptees looking for their birth mother are more likely to have a difficult time than domestic adoptees. There are, however, organizations and search groups that have experience conducting international searches.
Not all searches will yield a reunion or meeting between an adoptee and birth mother. However, you never know unless you try. Finding a support group to help with the emotional consequences of searching is suggested by most adoption professionals.