Telling your other child(ren) you're pregnant..

Megan
I am 4 weeks and 2 days.  We have a 3 year old little girl (will be 4 in a few weeks).  I became pregnant when she was 11 months old, but unfortunately lost that baby around 7 weeks.
I am so thrilled to be pregnant again! I shared the wonderful news with my daughter, and my husband thinks it was a horrible idea.  He said she will be crushed if we lose this pregnancy too, and how will we explain it to her? He feels he is being cautious and I feel he is having a negative outlook!
Pregnancy is a beautiful thing and we are lucky when our bodies give us this opportunity. I am excited about this and love being able to share the excitement with my daughter.  I did explain the caviat that "some babies are only in their mommy's tummy for a short time, and have to go back to heaven before they are born" only after my husband became so upset.
Am I wrong?  I know some people wait until after the first trimester to share the news, but what about with your children?