Dehydration is a common cause of low amniotic fluid levels. So are stress and smoking. Fluid levels can also fluctuate week to week, so they may be low this week and normal the next. The only time you need to worry about low fluids is if they drop really low (single digits for most doctors is a sign to monitor them for a few weeks) and STAY low. I had low fluids with DD- after they dropped they only came back up to about 8%, and that was after two + weeks of bed rest (stressful job WITH a smoker- perfect combo lol) and doing nothing but drinking and peeing. The lowest they got was just above the 5% mark my doctor gave me for "we're going to induce right away". We made it to almost 38 weeks, we were shy by a day or two when they induced me. I fully agree with PP, though, drink lots of water and relax. They will probably (depending on how far you are) want you in every week for checks if they are concerned.
at 3:42 PM on Oct. 16, 2010