Have you told your big brother or sister to be?

I have a five-year-old son is going to be six in December. ever since his daddy and I got remarried in March or this year he has been extremely adamant about wanting a baby sister and brother. Lol we asked him about how he feels about me and his dad getting remarried he said he was really really excited because "now I can have a baby sister". I got a patient coming from and at my doctors this past Thursday but we haven't told our son yet. The main reason for it is because I'm only seven weeks and there's still a chance that I could miscarriage especially given my health problems but we also haven't don't want EVERYONE to know right now since it's so early. Once we tell our son that the end of the "secret" everyone and I do mean everyone will know that I'm pregnant.

I was just wondering about this did you tell your child and how did they respond?