The general rule does not apply to foreign sovereigns, accredited foreign diplomats or their families since under International law they
are not subject to the law of the foreign country which has received them. Accordingly, children born in the United States to such individuals are not entitled to United States citizenship.
...
Accredited diplomatic officials are only those with recognized diplomatic status
and immunity, and include ambassadors, envoys extraordinary ministers planipotentiary, ministers resident, commissioners, charges d'affaires, counselors, agents, secretaries of embassies and legations, attachés, and other employees attached to the staff of the embassy or legation, as well as members of the Delegation of European Communities. The term also includes persons with comparable diplomatic status and immunity who are accredited to the United Nations or to the Organization of American States, and other individuals who are accorded comparable diplomatic status.