Establishing U.S. citizenship for a child who was born abroad may depend on the relationship between the parents at the time of the birth. It may also be affected by the citizenship of the parents at the time of the birth. California parents may want to keep these issues in mind if they will be out of the country near the time of a baby's due date.
Unmarried parents face greater challenges in establishing a child's citizenship than those who are married. In all cases, at least one parent must be a citizen at the time of the child's birth. The greatest challenges arise if an unmarried father is the only U.S. citizen as a legal blood relationship must be established. An unmarried parent who is a U.S. citizen at the time of the child's birth must also have spent a minimum of five years present in the U.S. or its territories. This can include employment abroad through the U.S. armed forces, the federal government or other specified international agencies. At least two years of residency must have occurred after age 14.
If both parents are married at the time of a child's birth, a parent through whom citizenship will be established must have been physically present in the country or its territories for a minimum of five years with two years occurring after age 14. If both parents are U.S. citizens, at least one must have lived in the country or its territories before the child's birth.
Parents may need to establish a child's citizenship before returning to the U.S. with the child, meaning that documentation may need to be submitted at a U.S. consulate or embassy in the country in which the child was born. If a parent is not prepared to prove his or her citizenship, it may be helpful to coordinate with citizenship attorneys who can gather the needed materials and assist in the completion of necessary applications.
Source: U.S. Citizenship and Immigration Services, "Citizenship Through Parents", December 31, 2014