What Ive learned on baby announcements
In modern times, anyone may be receive invitations. One consideration is to send out invitations to people who know the mother well enough to buy something appropriate for the new baby. Also know that invitations sent to people who do not know the mother are likely to be considered a bit rude. On the other hand, not only those very close to the mother may be sent invitations. It is advantageous to be on friendly terms with a neighbor for many reasons, and a baby shower is great way to start a new relationship with them.