Some of the advantages of having a small family are: More privacy, more attention from the parents, less financial troubles, more stuff, less need to share...
What Are The Advantages Of Having A Small Family?
If you are speaking about young children,one advantage if you like to help others they are dependant, and if you are asking about a family small in size ie 1 child or 2 children, the advantages to me is not very many, since I enjoy the company of a large family, but one advantage would be a lot cheaper to raise a small family......the best to you