HI Jessica
I worked to 37 weeks (teaching Prep children) with my 2nd. I was actually planning to go to 38 weeks but was too exhausted so I took a weeks sick leave.

With my 3rd I worked to the end of term 4, I was 32 weeks, but being Summer I couldn't have worked much longer as I was absolutely buggered.

Sometimes the work demands and hours and also driving time are the factors which will help you choose when to stop work and your body should also tell you
Cheers Michelle