UAB or UAAB - Unassigned At Birth, also Gender/Sex Undesignated At Birth (GUAB/SUAB) or Unassigned Gender/Sex At Birth (UGAB/USAB).
This term most commonly refers to babies who do not have an assigned gender at birth. It can be used by parents who are raising their children without a prescribed gender, though it may be used for other reasons. It may also be adopted by someone who doesn’t care about or pushes away their "birth sex".