Determining and Transmitting US Citizenship
Your child is an American citizen if he or she was born in the USA.
Your child is also a citizen if he or she was born abroad and both parents are US citizens at least one of whom resided in the US or possession.
If only one parent is a US citizen, that parent must have been physically present in the US or possession at least five years prior to the child's birth, at least two of which were after the age of 14. (For births before 14 November 1986, the American parent had to have been physically present in the US for at least ten years, at least five of which were after age 14.) Note that starting June 12, 2017, due to a Supreme Court decision, new rules apply for children born to unwed American mothers.
Other rules apply for children born out of wedlock or born before 1952.
As a general rule, children born abroad to a US citizen parent or parents should have their birth registered at the nearest US consulate before age 18. If your child was registered at a US consulate at the time of birth and you wish to replace or amend this document (DS-1350 or FS-240 "Consular Report of Birth Aboad") you can access the Washington Office of the US Department of State using this link: travel.state.gov
Your child born abroad may perhaps not qualify for US citizenship at birth because the American parent(s) has not satisfied the US presence requirement. There are two methods for possibly having your minor child (under age 18) naturalized as a US citizen: The Child Citizenship Act of 2000 (child immigration) and naturalization under Section 322 (using Form N-600K). One or both of these methods may be applicable in your case.
This ACA webpage updated March 16, 2018