Are there any other birthmoms out there?

My husband and I adopted an infant daughter and she is our joy. She is almost able to drive now and in a few years, will leave the nest. It is a closed adoption, but I send a yearly photo and update via a social agency to her birthmother. So far, my daughter has no desire to write, but we have never kept it a secret. When she is of age, if she wishes to make contact, we will help make it happen. Her birthmother calls her by the given name she named her and tells her of her love. My spouse and I are not at all threatened by that. She has a biological mother and she has a mom who raised her. We are both important in making her who she is. I am grateful her birthmother made the greatest sacrifice of her life in giving her up.