It's not always known why this may occur. Especially if you don't feel as though you are leaking the fluid (wet panties)
Some feel as though if you are not taking in enough fluids this may cause it. So do increase your fluid intake. Generally an ultra sound is done to monitor the situation as well. So if your doctor schedules these, make sure that you follow through with them.
There may be a placenta problem. If you are on any medications this may cause it as well. It could indicate situation with the babies kidneys... There are different causes..
Hope this helps, If you need anything else please feel free to ask. If you found this helpful don’t forget to click the *accept* button!