Michigan Compiled Laws, Chapter 722. Children § 722.1802

(a) In a record signed before, on, or after the birth of the child by the individual who gave birth to the child and by an individual who intends to be a parent of the child. An acknowledgment of parentage under the acknowledgment of parentage act, 1996 PA 305, MCL 722.1001 to 722.1013, is a record within the meaning of this subdivision.

(b) In an agreement entered into before conception that the individual who gave birth to the child and the individual who intends to be a parent of the child intended they both would be parents of the child.