Any other moms advice welcome

So I will be 30 wks tomorrow with baby #3. She is healthy and such but my question is. Have any other moms had a baby produce to much fluid? I'm now being monitored weekly for it. Drs are saying as long as she moves like she should and stays above the 20th percentile she's staying in as long as she can. They don't know why she's producing so much extra and they aren't saying anything is wrong with her just truly curious if anyone else has dealt or is dealing with this. What was the course of action in your case?