We were told the same thing with one of our twins. However, after 3 weeks of drinking a gallon of water a day, our DD still has less than her brother, but is within the normal range. Our peri told us its just a wait and see. Good Luck. I know how hard it is to wait.
this just happened to me yesterday at 19w. I'm pg with twins and one has low fluid. other is fine.
I didn't get a # of how low the fluid is. will need to ask. I was just so shocked yesterday by the news that I didn't think to ask for details.
I was put on bedrest now and told to drink "a lot". go back for another u/s in 1 week.
thanks for asking question and thanks to other posters for responding. I didn't know what "a lot" of water meant. Glad to hear that your babies are hanging in there and things improved with rest and increased water intake.