TO SOME adopted children, there may come a longing for relatives whom they have never known but to whom they are specially bound: their birth parents. The desire to find a natural mother and father may show itself even when the adoptive home has been a loving one.

Until the late '70s, the search for birth parents was impossible. The confidentiality of adoption records was an accepted fact -- and with reason. Parents relinquishing children wanted to be assured of privacy in later years, and those adopting them sought the security of knowing a baby was finally and permanently their own. In recent years, however, the movement to unseal adoption records has grown.

The states are responding in a variety of ways. Alabama and Kansas allow any adult adopted person to obtain his original birth records. Pennsylvania had a similar law for six years, but this month it amended the statute to require courts to contact birth parents and obtain their consent prior to any disclosure. This search and consent procedure is used in six states; 12 others have registries where all parties can file consent agreements if they wish to make contact. All other states, including Maryland and Virginia, and the District of Columbia continue to guarantee the confidentiality of birth records, though some provide exceptions for medical information.

Meetings between adult adoptees and their natural parents can run the gamut from joyous to disastrous. But the reunion can be traumatic for adoptive parents for whom the terms of a lifetime agreement may thereby be altered dramatically. Surprise is almost always a guarantee of trouble. A requirement for thoughtful consent is a minimal prelude to a successful meeting. A natural parent's right to privacy about an event that is always painful to remember is just as important as an adoptee's right to know every detail about his own background. Pennsylvania's decision to move from open records to a more orderly, humane system that protects rights and facilitates contacts should instruct other states considering reforms.