Or the Borg!
It didn’t bother me until I became pregnant. Now it grates on me. If my husband could take even 1/10th of my pain and discomfort, then he’d be allowed to say it, but until then, I’m the only one who’s pregnant.
To me the ‘we’re pregnant’ would indicate a total commitment and acknowledgment to the child from both parents. It is making a clear statement by the man that this is my child (too) and I am caring for the child through care of my wife/g/f while the child is in-utero.
‘She’s pregnant’ has too much a uncertainty to it, leaving paternity in question and almost like saying I left her along for a few hours and this is what happened, or like it’s all her now - I’m going to shoot some pool. It is also perhaps somewhat of a separation that one may use to distance himself from the child.
Now there are women who go through pregnancy unsupported and they have the right to ‘she’s pregnant’ but if the man is committed to his wife/gf and child, ‘we’re pregnant’ is appropriate, sensible, honorable, and understood in terms of what it means for either gender.