For the purpose of applying for Portuguese citizenship, birth certificate are valid for 12 months and FBI reports are valid for 3 months
US birth certificate
A certified US birth certificate can be ordered online here
https://www.vitalchek.com/birth-certificates
Differences in Birth Certificate Types
FBI report
It is not recommended to issue FBI reports directly from the FBI as it takes 3 months to arrive.
It is highly recommended to use an FBI-approved Channeler, which takes 7 business days to issue the report. Such a channeler which our clients have good experience with is
https://www.nbinformation.com/
Apostille
Both documents, before they are submitted to the Portuguese government need to get an Apostille
Our clients have good experience with these companies that provide Apostille services