Most international and some American infant adoptions are Agency Adoptions. In an Agency Adoption, after the birth of the child, the Birth Mother signs legal documents giving the right to place the child for adoption to a licensed adoption agency.
This agency may be in Minnesota, in another state, or in a foreign country. The agency then is legally in charge of the child until the adoptive parent goes to court to complete the adoption.
In an American infant adoption, because the agency has legal control of the child, they can set criteria which the adoptive and birth parent(s) have to meet. For example, they can decide that adoptive parents must be a certain age or a specific religion or have stopped infertility treatments before they can adopt from that agency.
They can also require a Birth Parent to do certain things, including requiring that the Birth Father be named and involved in the adoption process, which are not required by law. Always ask any adoption program what their requirements are before you begin working with them.