I believe, as long as ypu baby is within the lbs the diaper calls put. You should be fine.
@Lizbeth I mean my mom thought me that it should fit up to his belly button and shouldn’t leave redness or marks on his legs which the size 4 was very much doing. And he was also having crazy blowouts even if it was just a little bit of poop on the diaper. Now he looks comfy to sit and jump more (which he loves doing all day long) Also every time he was sitting with the size 4 you could see the straps under the whole belly so I was pretty confident about sizing up until the moment I started seeing all those comments and I thought I was putting on a diaper that was too big.
Every baby is different! My daughter was a very tall/long baby and at 4m was wearing size 9-12m clothes lol. If your baby is a gorgeous chunk and wears size 5, embrace it mama! Don’t compare with other babies, it will only upset you for no reason. Could just be your baby wears a size 5 earlier than others and for longer. It matters not as long as baby is comfortable and the nappies fit, ignore any unwanted comments and don’t give it a second thought.
i agree with Neena!! we got some healthy chunkers and we should embrace their little rolls because before we know it the little rolls are gonna stretch out when theyre running around everywhere and causing trouble bigger than blowouts! i had to return like 4 boxes of size 2 diapers to target and exchange for bigger bc i didnt realize how quickly she would gain weight especially since she was born 6lbs 7oz 
@Neena thank you I thought that it was me not knowing how to pick the right size and mine is also wearing size 12 or 18 months clothes sometimes.
@Lizbeth i love his little rolls he’s a little giant. At the moment when I’m sitting and he stands up on my legs his head reaches the same height as my forehead! and you both are right I’ll just keep doing it the way I did until now. He looks happy and free to move and jump and there are no blowouts so that’s all I can ask for
Not my Sept baby, but my 2 year old is 19lb and in size 3 nappy pants. If the nappies are leaving marks or they are leaking then definitely worth going up a size.
Omg the thighs I love it!! 😍😍😍 I believe it honestly depends on the brands as well. Every baby is different though so they fill out diapers differently.. my baby is 5 months and still in NB I tried the size 1 on multiple occasions but he is swimming in them.. it looks like your using Pampers? I do know pampers fit smaller for my baby but Huggies fit a little bigger.. so while your baby is a size 5 in pampers he might be a 4 in Huggies.
Them sizing on the boxes is crazy wrong. My 18 pounder in a 4 or 5 lol my 17 month old is in a 5. So just depends on whichever I grab first atp
At three months my son was in size fives. I was using the pampers 360s (elastic pull up style) and smaller sizes left red marks on his legs. He did not have leaks in them. He had really chunked up before he hit his next growth spurt. Now he has grown taller and his thighs have slimmed down, so much that we are back in size fours. Don't worry just keep him comfortable 😊
my baby girl is 5 months and almost 20 pounds.. were in size 3 and im thinking i wont buy anymore after these r done and go to 4! u want them to have room for blow outs that wont leak hahahaha