How is child custody determined?

First of all, its not clear as to whether or not you were married at the time that you became pregnant with this child and just who is legally recognized as your child's father.  That having been said, AZ like most states, determines child cutody and placement by the overall "best interest of the child" standard. Accordingly, the court shall consider all relevant factors, including: 

• The wishes of the child's parents as to custody.
• The wishes of the child as to the custodian.
• The interaction and relationship of the child with the child's parents, the child's siblings and any other person who may significantly affect the child's best interest.
• The child's adjustment to home, school and community. 
• The mental and physical health of all individuals involved.
• Which parent is more likely to allow the child frequent and meaningful continuing contact with the other parent.
• Whether one parent, both parents, or neither parent has provided primary care of the child.
• The nature and extent of coercion or duress used by a parent in obtaining an agreement regarding custody.
• Whether either parent was convicted of an act of false reporting of child abuse or neglect.
• Whether a parent has complied with state law regarding custody. 
   

Since you are seeking legal advice related to an AZ child custody matter you will want to consult an attorney in your area about your specific situation, where you stand legally, and what your legal options are.