I hung the sign because our dog charges the door barking when the doorbell rings, not necessarily because we have such a loud doorbell that it would wake a sleeping baby. (Although as a brand new mom I was sure the ring of the bell was enough) At first, the sign read only, "Please Do Not Ring Bell" and hung above where it is in this picture but after several people simply knocked, and the FedEx delivery man rang the bell anyway, I added the words "Or Knock" and moved the sign on top of the bell so someone wishing to defy my orders would have to actaually depress the sign when ringing the bell.
People who came to the door and saw this sign, whether they were selling something, making a delivery, or wanting to meet us and invite us to a party, most likely understood why the sign was there. But it's possible that someone found it to be cold or unwelcoming. That's why when I found the Hobby Lobby sign I was so excited. Now when someone comes, they see a friendly little request to please go away, tied up with a pretty bow!
Back to why this is perfect for new parents. When we first brought our baby home, I was essentially in the house with him for weeks and whenever I realized that I needed something, I ordered it online from Amazon. Because I had the free two day shipping that you get when you join Amazon Mom, there was a continuous stream of packages arriving for those first months. In order to make sure that my doorbell wasn't ringing three times a day, I needed that sign. Other parents might need it for a different reason. Although we didn't have this problem, many new parents find that their family and friends stop over univited to help out or see the baby. As a first time parent, they might not know how to express that they don't want visitors, don't want to entertain, or just simply want to be alone with their tiny new baby. Giving this sign would be giving them the ability to gently hint that it isn't a good time to be dropping in on them without having to step on the toes of well meaning friends, in-laws, or neighbors.
No one will know if the sign hangs 24/7 and not just when the baby is sleeping unless they drive by on the hour waiting for it to be taken down. In that case, if they want to see the baby that bad, it's best to just let them in- but they better be bringing food!