Hi. Sometimes when chicks hatch they can have swollen belly where they have absorbed the yolk. Or your chick could have mushy chick disease have a read of this link to see if your chick has any of the symptoms.https://www.backyardchickens.com/a/mushy-chick-disease-yolk-sack-infection-omphalitis. Hope this helps and good luck with your chick and hatch.
Hello! Congrats on your new baby! I just had 5 hatch in the past couple days
Anyway, I had 1-2 with a larger belly, they only occasionally went backwards, but I just kept an eye on them and they turned out fine, running and as peppy as ever. I do believe that it's just the yolk sack still absorbing and whatnot, but one of the chicks with a big belly just had a natural big belly because he is a plump & large chick