Is this behaviour normal or something to be concerned about.

[M212]

Anxious first time mother. My 7 month old boy seems to be doing things that I have never seen other babies do and other people make comments about. For the last 3 months he straightens arms and legs and slightly shakes while opening and closing his hands. He does it multiple times throughout the day and is worse when excited and cross. He does it while lying down while in jumperoo while sitting on the sofa anywhere really ! He will react to you when you talk and often makes a noise of some sort while doing it. Should I be concerned.Convinced myself he is displaying signs of autism. Can this be possible at a young age ?
he is able to roll however can’t sit unaided. He reaches for objects and enjoys playing with toys. He responds to his name most of the time and has started babbling (dada) (lala). He shows little interest in spoon feeding and refuses most days but will chew on melty sticks and rusks. He engages well with others and smiles and laughs during same .

Just to add it is a humming noise he makes while doing it happens very often

Hi there,

you say he is not sitting unsupported - does he flop over entirely? Or can he prop up on his arms a bit and keep his neck up?
does he roll from tummy to back and vica versa?

Do the movements seem involuntary? Like he doesnt have control over them?

I've not come across the other issues but would think he should be sitting at 7 months.

Have you had much contact with the HV?

Dd2 didn't sit until she was nearly a year because whenever I tried to get her to sit, she threw herself onto her front and crawled off. She crawled at 5 months. I suspect it may be similar for your ds if he's moving.

Opening closing hands (and twirling wrists) when emotional (excited/angry) is normal.

Keep an eye on the not sitting, but there's nothing here that puts huge flags up.

He can keep his head up no problem he can roll belly to back and back to belly no problem. He throws himself backwards when trying to get him to sit up or falls to the side.
movements are not involuntary he definitely chooses to do it. He is not yet crawling.

Okay, definitely dont worry about the not crawling yet.

keep encouraging sitting - prop him up with cushions or just practice sitting between your legs while you long sit as opposed to having him completely supported in a chair to stimulate the muscles. Also do plenty tummy time and rolling over for trunk strength!

if you have a walking ring, dont use it more than maybe ten minutes at a time couple times a day, it doesn't aid development.

throwing himself back when coming into sitting and straightening limbs sounds like he just hasnt yet integrated some neuro reflexes - particularly STNR if you want to read on it… when you position him in sitting, bend his legs in cross legged position to avoid that push back reflex and have him lay over your out stretched leg on all fours encouraging head lift.

Sorry, didn't meant to imply that he should be crawling. Dd2 was very early (and tbh a complete pain) - dd1 wasn't crawling until after the age dd2 was walking, and dd1 was very much in the normal range.

But by the sound of it, it's similar to dd2. She threw herself forward if you tried to get her to sit. He throws himself backwards. That means simply he isn't getting the practice - and there isn't a lot you can do.
Dd1 sat beautifully because she loved to sit and watch, so she became very stable quickly because she did it a lot.

What I found with ds (more similar to your ds) was that sitting him between my legs and doing something with him (building towers he could knock over was a good one) was the most encouraging way of helping him sit. He still was ages before I could leave him entirely on his own to sit, but it helped.