It is completely fine to have a baby that small and have them be full term. My son was premature and he was born at 31 weeks but he was the size of a 26 week old, which put him at 1 pound and 13 ounces at birth. He survived and is doing great. There are plenty of babies that are born a little on the small size. If you take a look at some of the onsies on market these days for new borns the weights for the onsies say 5 to 8lbs just because of the fact that babies are all unique and different and they don't have to be a set size. Also if this is your first I would like to prepare you by telling you that your baby will lose a little weight once born but will quickly gain it back which is normal. All babies lose a little weight after being born. Enjoy your baby and try to relax. It's not good for your baby if you are stressed out about the little things.