Any babies with fluid in the brain ?

Our 26 week scan detected 0,51cm fluid on the brain. The doctor said it's absolutely nothing to worry about because it's in normal range and anything above 1.0 cm is high, 1,5cm being very high. I've read up on it a bit and seems that some babies just have it and eventually it corrects itself. If it doesn't though it could lead to many complications like brain damage. Has anyone else had this? I know mine is in the low range but it still has me worried.