The birth of a first child is a crucial, founding event in the creation of a family and in the daily and social lives of couples. The study presented here assesses the effects of this event on social networks and communication practices. It also examines how the actors themselves use communication tools to manage, maintain or even select their networks of relations. The analysis reveals two hierarchies - one of interpersonal relations and the other of modes of communication - organized around the baby's birth. These can be seen as a norm or language through which closeness or distance are expressed. The young parents' interlocutors identify their position in the couple's network by the tools and modalities chosen to interact with them.