such a tough question
I personally told as soon as the lines were there -- in fact sis knew before DH cuz the first test was sooooooooooo LIGHT.
But my feeling is -- if something happnes, and it does happen fairly often in the first 12 weeks, i would be a wreck anyway -- as i would not / could not hide the loss and the upsetness, i see no reason to hide the joy.
but THAT is something to consider. you have to untell -- I have a freind who just lost a baby, and she told me of the MC but i had not known of the pg .... this way she only tells who she wants to know of the MC .. YK???
and things do happen a lot more than some peopel think -- more than i used to think
Sis had a MC with her very first pg... she was more catious the next two time (both healthy) but she is more private in her loss, and didn't want to deal with the DH's co-workers and so on.
DH would not tell work, with either of ours till week 12.
then you take into account -- what reaction are you expecting? My baby sis is due with her 3rd and she waited longer to tell than i did with #2 (I am older by 3 years) cuz her in-laws we all knew would give her grief (and they did)..................
it is so personal and depends on so much.
If i get pregant again, and Theo and / or this new baby are old enough -- I will not tell them till wekk 16.... after most MC risk is over. But that is a varaible = kids.
but -- I did tell 10 days past O date.