Terrified 20 week scan and short femurs

[Mrs777]

Has anyone got any experience with this? Had my scan today and everything is fine all measurements and heart etc but the femurs are measuring the 3rd percentile. I’ve to have another scan (bone) one tomorrow.

Good luck tomorrow - scan can be very inaccurate. We were told our DS was worryingly small at 29 weeks. The dr said that the femur was the measurement that was most likely to be inaccurate and to be more worried if the head was measuring small. After another worrying scan a few days later I got steroids to get DSs lungs more ready for birth only to find in the final check that his size was fine. He was born at 39 weeks a bit bigger than average.

Thank you, I’m just beside myself. I’m glad everything was good for you. Congrats on your son.

Hi I was told short femurs in the last couple of months of pregnancy as in <5th % tile. Like you I was terrified. All was fine in the end. Child going to be very tall with long legs (ironically) I expect. I hope your mind can be put at rest soon and next scans

Thank you she’s just scared me as I’m 42 and she said it’a usually genetics or Down’s syndrome

Me! I’m currently 36 weeks and at my 20 week scan everything measured fine but femurs were just above third percentile. The baby was also super stubborn and wouldn’t move so they couldn’t finish the scan which added to the anxiety. I was a wreck so I know how worrying it can be.

We had to go back at 22 weeks to have our repeat scan and all was fine and then again at 23 weeks to measure the legs again. The legs were on the 4th centile overall at that scan but had grown in an upward trend along the rest of the chart which is more important than actual measurements. At this stage the difference between the 3rd and 50th percentile is literal millimetres. It’s about tracking and seeing if the legs are growing on a steady trajectory rather than tailing off or falling even further behind. We’ve since had growth scans at 28 weeks, 31 weeks, and 34 weeks and the legs have consistently been growing on their own growth curve but have always stayed below the tenth percentile. Head is always above 60th and abdomen is always right around average at 50th. I think their legs are on the 6th currently. The consultant is happy that their legs are just short. Like all humans, we don’t have the same proportions - some of us have long legs, some of us have short legs etc. That’s why they do the range from 3rd - 97th percentiles as someone has to be the shortest and someone has to be the tallest. A few things that helped me to cope:

1. 3rd percentile is still normal - it’s just at the lower end of what’s considered normal at this gestation. It means of 100 babies born 97 would have longer legs than your baby. That’s human nature.
2. At this stage the legs are being measured against the national average growth charts, they have been customised to your individual build yet which they’ll do from 28 weeks. My baby’s overall measurements dropped percentiles from 32nd overall at 23 weeks to 17th at 28 weeks and most recently at 34 weeks were on the 14th percentile even though they’re almost 5lb because I’m 5ft7 so they expect the baby to have a larger build. They don’t take into account my husband is 5ft8 and has short legs. If you or husband are shorter then it’s probably just their genes.
3. Measurements can have error margins of 15% because the measurements are so small and there’s so much room for error. That’s why they check and check again.
4. It’s less about centiles and more about interval growth. If everything is growing on a steady upward curve, even if that curve is on the lower centiles then it shows that the baby is growing as expected and that’s what doctors look for.
5. At this stage, the body prioritises head and abdomen growth over legs because that’s where the vital organs are. The legs sometimes catch up later.

Hope this helps and hope all goes well at the bone scan tomorrow xx

At one point I was told that dd had no femurs at all!!!!! 😱
I can confirm she does in fact have femurs, but she is just short.

Hi try not to worry too much, am 30 weeks and have been through amnio etc having had baby identified as 3rd centile for growth at 20 weeks. It was very stressful, but baby has no identifiable chromosomal abnormalities and I think it's the femur length that's making him 3rd centile. Femur length by itself isn't a useful signifier of chromosomal abnormalities, it should be taken with the risk identified with the combined test, and anything else going on with you, e.g. I have high blood pressure, and am older than you!

Speak to your midwife/sonographer and try and get a more rounded picture of your risk level - don't panic based on femur length alone. And easy to say but you may want to step away from the Internet too - listen to what your medical professionals say.

Good luck 😊

Thank you everyone 🤗 After numerous losses one weeks before this pregnancy I’m just so scared and have been “waiting” for something to happen almost, should I be worried she got me in for a scan the next day?

Don’t panic, most likely it’ll be absolutely fine. Getting you in the next day is great, it means they are taking good care of you.

My son had femurs in the 2nd percentile, head and abdomen in the 95th and is fine. Did you have a NIPT done?

I’ve had the NHS screenings which were low risk

So everything else is normal it’s purely his short femurs, she said she has to offer us the amnio, said her son had the same and was fine. So torn what to do. Have the amnio or have a rescan in 4 weeks and just hope for the best.

I was 40/41 …

How tall are you and your baby’s dad?

I am 5.2 and my husband is 5.11

They said exactly the same about my first daughter. She came out with little legs and a long body but a perfectly healthy everything else and she is a strapping 25-year-old. 5 foot eight

With your height it’s not unrealistic for your baby to have short femurs! Your screening was low risk. I think you’ll be ok 😃

I am just so torn what do 😞

Why would you do anything? Scans are notoriously unreliable and in any event why would it matter? Short people have happy and fulfiling lives too.

She’s quite short herself!

The consultant wants to do an amnio incase he has Down syndrome, I’d like to know one way or another but I’m scared to do the amnio incase I loose him.

They can test for downs when the babies actually born. Yes, it’s difficult not to know for certain before the birth, but before all these modern tests we just had to wait like everybody else in the world. Even if Downs is present, it doesn’t sound like they spotted any real issues that would mean actual harm for the baby e.g. holes in the heart or anything. So why would you take the risk?

Unless things have moved on massively in the 25 years since I had a child
I wouldn’t be risking it. I wouldn’t be doing anything that would risk losing the baby at all.
If the baby has down syndrome, what are you gonna do with that information?
Do you care ? does it make you love the baby less?
Would you abort?
If the answer is no then what is the point of risking his life?

I would pay for a NIPT test before doing an amino. It’s less risky and still gives much more detailed results.

If they can’t see any bone abnormalities, or dysplasia, and your other Down’s syndrome markers from the combined test have come back low then the risk is probably low. Shirt femurs on their own are not a marker for Downs.

I know the wait feels agonising now, waiting until 23 weeks for my growth scan was awful. If you can, I would definitely reach out to the perinatal mental health team at your hospital. They are there purely to ease anxieties in pregnancy and they were amazing when I was in the same position and explained everything really clearly.

Just remember that femurs on the 3rd centile are still within the parameters of normal growth - especially since neither you or your husband or particularly tall. I remember going for my scan at 23 weeks when the baby’s femurs were measuring just above 3rd percentile (3.6) and the consultant wasn’t even sure why we’d been referred because at this gestation there’s so many variables with measurements and whilst 3% is the cut off it’s still normal. As he said “someone has to have short legs, we can’t all be giants”. I think the difference between our baby being on the 3rd of 50th was something like 2mm difference. It’s so small and there’s so much margin for error with scans.

Obviously you should do what you feel is best but I would definitely research the risks and benefits of doing an amino at this stage vs waiting a few more weeks. Get a second opinion. Also Jsut give your brain time to process. I know it’s overwhelming and you want all the answers now because the uncertainty and worry is crippling but there is support out there to help! Xx

Take the tests or you’ll spend the whole pregnancy worried sick.