The first time, I was 5’9" and 125lb when I got pregnant, so not like I had anywhere to hide it, but I worked until 6 months without telling anyone and that is when it became impossible to hide.

The subsequent times it happened faster, the belly was noticeable by 4 months or so, I could feel it before anyone else could tell in all cases.

I had a history teacher who was hugely fat - she warned us she would be out on maternity leave, we thought she meant later in the year but she was gone the next week, and when she came back, looked no different at all.