You need to talk with an attorney practicing family law or adoption law in Utah. You should be able to contest your signing of a release of parental rights at the hospital; however; it depends upon how you came to this decision. Were you working with a social worker from an adoption agency or is this something you decided to do only at the hospital. If you worked with an adoption agency who had a social worker counsel you, then you may have a hard time contesting the voluntary release of parental rights.
This information is not intended as legal advice and is intended only to provide the questioner with general information. This is not intended to answer any other questions with similar facts. This is a general answer and does not create an attorney-client relationship or an attorney-client privilege.