You must register your child’s birth according to the regulations in the country where the child was born. They will give you a local birth certificate.
Once you’ve done this you may be able to apply to register the birth with the UK authorities.
You don’t have to do this, but it means:
- you’ll get a UK-style birth certificate for the child
- you’ll have proof that the child is a British citizen
- the birth will be recorded with the General Register Office in the UK
A locally-issued birth certificate should be accepted in the UK for all purposes, eg applying for a passport, registering with a school or doctor etc. It might need to be translated and certified if it’s not in English.