Birth parents looking for adopted children have a few search and reunion options. If the birth mother placed the child with the help of an agency, she can return to the agency and ask if they have post-adoption services that help reconnect birth parents looking for adopted children. Some states, however, require birth parents to register with the state registry, which keeps track of all members of adoption parties searching for one another. State registries usually run on mutual consent, meaning that as soon as two parties register in search of the other they will be given basic contact info for the other or will be given access to an adoption record with the purpose of searching.
Birth parents can also attempt to reach an adopted child through the help of a private investigator. However, many details relevant to the child's new lifestyle and identity will be difficult to locate because a new birth certificate is issued to the child during the adoption finalization process.
It's also possible to petition the court for a confidential intermediary to access the adoption records and facilitate a search and communication between birth parents looking for adopted children. Birth parents can also register with an online database that allows searchers to manually look through other registrants. Some online databases and search services may cost money. Be sure to research the integrity of these businesses with the Better Business Bureau before investing in something that will financially and emotionally drain you.