Short femur length 34 weeks

[CaBro]

Hi all,
I had a scan yesterday morning at 33 weeks 5 days, and everything was fine with our little boy (head, tummy, heart, umbilical cord etc) except his femur length was measuring about 5 weeks behind, putting it in the 1st centile. We've been referred for a more detailed scan with the consultant on Friday, but I feel absolutely sick with worry. I wondered whether anyone had been through something similar, and would be willing to share what happened for them?

We had this at our 20 week scan (head 50th, abdomen 97th and femur 3rd). We were sent to the foetal medicine unit who did a more detailed scan. The measurements there came back short but over the 5th percentile. They weren't concerned at all. We've had scans every 3 weeks since then back at our normal hospital and the femur continues to measure under 5th percentile.
Try not to worry, it's very unlikely that there's anything wrong. Short femur measurements are apparently very common and they think it's because the technology the machine uses has changed significantly since they first started doing ultrasounds except they haven't changed the way they calculate the measurement.

Thanks so much for this, that's really reassuring to hear. I guess we're particularly alarmed because at 20 weeks his femur was in the 21st percentile, so it seems like quite a drop. But I am trying to tell myself that there are a whole host of reasons that could be (including off measurements), and not to draw any conclusions at this stage. It's hard not to worry though!!!

Hi I'm 29 weeks, going through this right now. At 20 weeks our baby's femur was below 3rd percentile, at 22 it was just on the line at 3rd percentile, and 28 weeks it was back down below 3rd percentile at 49mm when it should be something like 52mm. Everything else has been perfect with the baby, AC being 70-90 percentile and overall weight at 50 percentile. I don't know what is going on, the consultants don't seem very concerned but I am! I'm hoping this is just because I am 5'2 and petite frames run on both sides of the family. But it is quite scary! I'm getting frequent growth scans now.

I had this, was lower than 5th but can’t recall exact number. They weren’t really growing either. I was very anxious. Nothing wrong in the end. Child still has short legs though!
I hope all is ok for you.

Oh - I have very long legs and very tall myself, which made me worry all the more.

@Farmhouse1234

Oh - I have very long legs and very tall myself, which made me worry all the more.

Yes! I am average height (as is my husband) but have quite long legs, and this is definitely feeding into my worry!

Thanks for your reply – really glad everything worked out OK for you. Keeping my fingers crossed for me and for @Xxdxx2020 (glad the consultant isn't too concerned)!

As per a PP, the difference in the centiles is millimetres. If there was something to worry about, I'm sure the hospital would have brought it up.

@CaBro how did your scan and consultation go? Xx

Thanks for asking @Xxdxx2020! It made me feel a lot better.

The consultant measured his femurs as slightly longer than the previous scan (6th centile rather than 1st), and said everything else looked like it was developing really well. She noticed that my placenta looked slightly calcified in some places, which suggests that it might not be functioning at its best, and that maybe the baby's prioritising head and tummy growth over legs. She was pretty chilled about it, and said that there was no urgent concern at all. We're having another scan at 36 weeks to check his progress – if his growth has slowed any more then we might have to consider early delivery after 37 weeks, but we'll cross that bridge when we come to it. Apparently if his leg growth has been a little bit slowed it will catch up when he's born, and in any case it wouldn't be noticeable!

He did manage to turn breech between the Monday and Friday scans, though, which is very annoying as he's been head down for weeks!!

How are you doing?

Just wanted to update this for anyone with this worry in the future - my little boy was both perfectly healthy and is now 2 and a half months old and growing like a champ. His height is currently 50th centile, and as far as we can tell there has never been anything disproportionate about his legs!

*born, sorry, not both!

Thanks for updating on this - so pleased to read your little boy was born with no problems! I had a growth scan today at 30+4 and have been worrying all day as they found the femur length to be on the 5th centile (with estimated weight also being under 10th centile as a result) whereas at 20 weeks it was fine. I've now been scheduled in for a Doppler scan and another growth scan. Husband is chilled but I can't stop stressing!

@ali912 I'm sorry to hear you're going through this stress. I ended up have 4 extra growth scans with femur lengths on the 1st, 6th, 3rd, and 5th centile respectively, and I stressed so so much about it, so I really empathise. In hindsight all the medical staff were pretty unworried - it was just belt and braces - and I wish I could have chilled out about it...but easier said than done! Presumably his femur were slightly on the short side, but at that scale it's a matter of millimetres, and as I say he's a very average length baby (no-one measures their femur after they've been born 😅)

Haha yes that is a good point! I'm hoping that the next growth scan will show things have improved a bit. But if not, I'll try to focus on your experience and not let myself get too stressed!

For anyone following this in search of answers: My baby was born, the cause was a marginal and velamentous cord insertion, diagnosed after delivery, causing growth restriction. He is perfect and healthy, fitting into all this clothes as expected, and developing perfectly. Such a stressful time but I'm forever thankful that he is here and healthy.

Really pleased to hear this! Thought I'd update as well. My baby girl was born 3 weeks ago and everything is fine - no problems with her legs and she weighed 8lb8oz, so her estimated small weight was not accurate at all!

Similar to this my kids both had short femurs, my daughters particularly so - hers was barely on the scale. However, I had no extra scans because back then it was all ok as long as it was consistent, and it was consistently very small.

My daughter was born (and continues to be) petite, but her legs are so long at the moment she looks like a baby giraffe when she gets out of bed 🤣🤣🤣 (she's now going on 9 years) my son also had short little legs (even when born they looked short!) but is now a petite (but normally lengthed-legged 5 year old!

Hi Everyone,
I am also going through this currently. Had my 30 week growth scan and babies femur is 50.9mm.. <2.5.
I am so worried - all other measurements are OK and on the chart.

I am 5ft and dad is 6ft 1. I am just praying she has daddy's head and mummys legs!

Did anyone else experience measurements like above? The radiographer scared me.. he said it could potentially mean she could be born with dwarfism or downs. I had the testing for downs, and it came back 1 in 100000.

Any answers would be great! thank you x

Hi @LolMc our short measurements were at 34 weeks onwards, and I can't remember the precise mm, but his femur were under 2.5 centile for several measurements (1st centile by one measure). I too had a 1 in 10000 chance for downs and was told that short femur are a soft marker and that downs was v unlikely. In terms of dwarfism, consultant said that femur measurements would really really far off if that were the case. My LO was born healthy and nothing disproportionate about his legs; he's now 6 months, weighing on 75 centile, and busting out of sleepsuits legs first. I worried so so much about him, and wish I'd just enjoyed the last stages of pregnancy, but really appreciate that's easier said than done. Sending good vibes x

Morning! Thank you for sharing that. Sounds like your little man is just perfect.
It consumes your brain so much its making me stress and unfortunately not making me enjoy the last part of my pregnancy.

All her other markers are on the small side but she could just be like me! That's what i am praying.
I have a private growth scan on Friday and hoping they give us some more info! Xx

Hi, that’s really reassuring. Do you have any updates??

Hi all...update I had an emergency c section as the also missed that my placenta wasn't working IGUR.

She was 4lbs spent 10 days in NICU due to hypoglycaemia and an infection. But was perfect. Now 5 months down the line shes small but perfectly healthy!

That’s lovely news - congratulations 🥰

Aw, that sounds very stressful but I'm so glad your little girl is doing well x

Hi all. Very reassuring hearing all these stories. I just had a 28 weeks scan and baby's femur is on border line 3rd percentile. We have been referred to fetal medicine at 12 weeks high NT then had CVS all came back clear. His 20 weeks anomaly and heart scan was perfect.

I am quite short 5ft 3 and husband is 5ft8. The consultant didn't seem overly worried as he discharged me from fetal medicine and referred me to another growth scan in 2 weeks locally. There's no any other anomalies detected he just put him down as short long bones worth monitoring. He also mentioned placenta blood flow isn't perfect but he wasn't concerned just watch movements - this could also be a reason of the shortness.

Husband is pretty calm but we went through so much during this pregnancy I'm just getting very anxious again this scan is.coming up! But wanted to thank you sharing all your stories..very reassuring.