Baby's weight at five months pregnant

Maelyn

So when I was 18 weeks I found out my baby only weighted 8 ounces I'm 20 weeks and a couple days I went to the doctor and gained just a little weight.( finally over 100 pounds) then I asked my family how much my baby weighted now and they all said about 10 ounces... I know it's below average but is is normal or safe for the baby?