I teach 4th grade. My first trimester will end the first week of school. Would you tell the parents of the kids in your class at the beginning of school/meet the teacher or wait until you start showing?
I would wait. Otherwise, it's sort of like saying, "Hi. Welcome. I'm your child's teacher, but I won't be here for the entire year." If there's not already a plan for a sub worked out, I would spread the info to the parents (they would likely have questions you can't answer). The news would just muddle the beginning of the year.
When I started the school year, I was 5+ months pregnant (with twins) and the first question I got from students was, "are you having a baby?" However, I never made any announcement to parents. A few asked me at open house, but it honestly wasn't a huge deal. Most of my students by that point, had had a teacher who had gone out on maternity.
Since you will only be ending your first trimester, I'd wait until you start showing.
I was about as far along as you will be when I went back to school last year. I teach K and it would have FREAKED some parents out if they knew I was pregnant at the beginning of the year (as it was one still freaked out when she found out I would be out for the full 12 weeks). Anyhow, that being said, I did not tell until I was about 16 week pregnant. In fact, the only people I told at school earlier were my principal and my assistant. Why? Because if your school is anything like mine, secrets don't stay secrets long. I knew that if the general faculty knew, it wouldn't be long before my parents found out.
I think that they will figure it out eventually, especially being 4th graders. I never told my students. My 2nd graders never asked, until one little girl pointed it out to a couple of kids near the end of the school year (and I was already 7 months pregnant). Some kids asked about it, and I told them that yes, I was having a baby, and that was it. I don't know, maybe it was because of my history with pregnancies, and I also didn't feel like it was any of their business. I know other teachers that told their students right away, and that is OK too, but I just didn't.
Re: Teachers - Telling Class?
When I started the school year, I was 5+ months pregnant (with twins) and the first question I got from students was, "are you having a baby?" However, I never made any announcement to parents. A few asked me at open house, but it honestly wasn't a huge deal. Most of my students by that point, had had a teacher who had gone out on maternity.
Since you will only be ending your first trimester, I'd wait until you start showing.