The U.S. Citizenship and Immigration Services (USCIS) and U.S. Department of State (DOS) have official reference materials which indicate what documents (e.g., Birth and Marriage Records) are available in each country and how those documents may be obtained. If these reference materials reflect that a specific document exists, then the document must be provided at the time the case is filed. You can find more information regarding what documents are available at the Department of States Visa Reciprocity and Country Documents Finder website.