I actually don't know the answer to this one, but just to encourage you, I was told on a scan that my baby did not have enough amniotic fluid....and that I could give birth despite a low grade placenta praevia - both of which proved to be incorrect interpretations of my scan.

Another time, we were told that my granddaughter's head was too large in circumference for that particular stage - again, there was absolutely nothing wrong with the baby.

So even though it's difficult, try to relax and adopt a wait and see attitude.  On the positive side, your baby has two kidneys and that's how it should be regardless of size.