B.R.
I had the same problem several years back. I did not tell anyone until I started showing. I think they already knew before I said it because I was about 5 months at the time. I would hear the whispering.LOL I had problems in the past so I did not want to say anything.
I eventually told my boss only because my pregancy was considered high risk and I was seeing my Dr.sometimes 3 times a month.