It's a personal choice. My mom worked until the day she went into labor with all 4 of her kids. (Her water actually broke at work with my brother). But it's all up to u.
If you feel fine then there's no reason to stop. I got signed off the middle of last week because I was hospitalised with pre-term contractions. I've been in.the hospital twice this week. I'm due September 15th. If this hadn't happened I was going to be finishing work next Saturday.