8 month old unable to sit up

[descendingintomadness]

My 8 month old DD is unable to sit herself up, or support herself upright if she is put into a sitting position. I have no experience of this as my DS was sitting perfectly at 6 months old, and whilst i know not to compare babies, all the books seem to expect her to be able to do this by now.

FWIW, my DD is a long thin baby (25th centile for weight, off the upper scale for length), not sure if this would make any difference? (DS was short and fat at the same age, maybe his sitting was more a 'weeble' effect)

Apart from this, she is developing well and not causing me any other worries (apart from her determination that no food other than her formula milk shall pass her lips despite all my efforts to the contrary!) - should i be concerned?

I would be asking HV for advice and reassurance if no progress by say 9 months

Has she had plenty of tummy time? They have to do lots of that 'aeroplane' thing - lying on their fronts raising/flapping arms and legs - before their back muscles are strong enough to support them sitting. Back muscles develop in three groups - neck, then thoracic, then lumbar. If she holds her head up well and can push up on her arms when she's on her tummy then I'm sure it'll come in time.

How does she 'flop' when you sit her up? We had this problem with our DS - every time we sat him up he'd fall backwards. With him the trouble was that he was trying to straighten his legs all the time, so he didn't get the hang of balancing. I can't remember at what point he got it, but it was definitely later than the books said.

How does she react when you prop her up against something? Is she happy to let it take her weight or does she fidget? If she's a fidget it could be something as simple as not wanting to stay still long enough to get hte hang of it. If she's a very placid baby she could just be a bit laid back about the whole thing, and not see why she should bother when there are all these things to do the work for her.

I'd say give it a couple of weeks longer, then go to the HV for reassurance. it doesn't sound abnormal to me, but the reassurance will help.

Thank you for your replies.

She has had lots of tummy time, and can push up on her arms (when she's not constantly flipping herself over onto her back). Yes, she does 'flop' when propped up, either backwards or forwards, but is constantly trying to sit herself up when she is lying down.

She is a very placid baby, and DS is very time-demanding, hence me not really being aware that she's got to 8 months old without being able to sit IYSWIM.

I'll give her a few more weeks, then run it by the HV.

My DD didn't sit until 9 months+ but she did have problems. Is there any other things you are concerned about?

Neither of mine were sitting at 8m. Both were long flimsy babies - a short bulky baby will find it far easier to sit up. I wouldn't worry yet. If they are still not sitting by 10m, I woudl try the HV, but still don't panic.

I have to disagree on a short bulky baby finding it easier to sit. DD wasn't skinny.

My dd had difficulties with sitting for quite a while due to low muscle tone in her back/trunk. She would go over backwards mostly when she straightened up her legs! We used a bumbo seat which helped strengthen the muscles. She is also a long flimsy child - she still looks very fragile even now she is walking!

My DNephew is coming up for 11 months but still does not sit up and the HV is not at all concerned. He is starting to commando crawl, hence why she's not worried as it appears that he'd rather be crawling than sitting.

I'm surprised about the comment about the tummy-time though, I didn't realise that was the case. My DD hardly had any tummy-time (she hated it ) but has been sitting since 6 months, but my DNephew spent LOADS of time on his tummy, but isn't sitting .

Every child develops differently, some will do some things before others.

OP - can she crawl?