If a person who has executed a consent to or relinquishment for adoption is under eighteen years of age at the time of the filing of the petition, and such infant parent is a resident of the state, the consent or relinquishment shall be specifically reviewed and approved by the court and a guardian ad litem may be appointed to represent the interests of the infant parent. The guardian ad litem shall conduct a discreet inquiry regarding the consent or relinquishment given, and may inquire of any person having knowledge of the consent or relinquishment. If the guardian ad litem finds reasonable cause to believe that the consent or relinquishment was obtained by fraud or duress, the court may request the infant parent to appear before the court or at a deposition, so that inquiry may be made regarding the circumstances surrounding the execution of the consent or relinquishment. The failure of the court to appoint a guardian ad litem is not grounds for setting aside a decree of adoption.