It's pretty straightforward really. You can of course use a gestoria like ours (www.servissim.com)but you can do it quite easily yourself.
If the parents are NOT resident in Andorra, they will only get an official birth certificate. Being born in Andorra gives NO right of nationality or residence in itself for the child (or its parents), unless the parents are themselves officially resident. In this case the child must go through the school system in order to be able to elect to take Andorran nationality at age 18, and give up all other nationalites. Andorra does not accept dual nationality.In the interim, the child will be entitled to an annually-renewable travel passport (laissez-passer)AS LONG AS the parents remain resident. Should the parents cease to be officially resident at any time during the 18 years, then all rights of the child to nationality fall away.
If the parents are indeed resident, all they need to do is to go to the civil register in Andorra la Vella and confirm the birth. Not difficult, not expensive. However, certain immigration obligations are also required, in order for parents to conform to specific provisions of the Immigration Law of 2012