Baby's Femur on 3rd centile line at 20+6 week scan

[GBrown7]

I had my 20 week scan last Friday. All my measurements came back as normal except the femur length which was 30.3m. On the chart its positioned on the 3rd centile line. Both midwifes have told me not to worry but I obviously am worried. I have been referred to The Rosie in Cambridge for more scans on Wednesday and have been told that if the measurement is still small, I will then need an Amniocentesis. I am worried sick which isnt helping me or the baby. I just wondered if anyone else has been in this position before?

[Flora631]

Hello, we were on the 5th percentile from 20 else’s onwards. I had scans every 2-3 weeks or so. It’s hard not to worry, but they were correct in saying weight it the most important measure. Did the midwife actually say amneocentisis or was that from google? Seems a huge step away from where you are at the moment for them to be throwing that in…

When my daughter was born her legs were absolutely fine. She’s little but not so anyone other than me would notice (I am only 5ft2 also)

[GBrown7 in reply to Flora631]

Hi thanks for replying, the midwife we saw on Friday said that they would give me another ultrasound at Cambridge and then if they were still concerned about femur length, they would offer me an amneocentisis to check for Downs.

I am 5'5ish and my husband is 5'6 so we arent massive. Google just flags up all these horror stories and it makes you panic.

Tomorrow morning cant come soon enough, just want this over and done with. x

[1sttimerph]

Hi, I too was open to fetal medicine. I was a nervous wreck during pregnancy, googled potential conditions. My little boy is shorter than average but fine I think all the science is great in ways but too much at times! I refused an amniocentesis. All the best! X

[GBrown7 in reply to 1sttimerph]

Do you know how long his femur was at 20 weeks? All this science is very clever but doesnt help!! xx

[1sttimerph in reply to GBrown7]

No mine came to light at 29 weeks. I then had scans around every other week. My little boy was also measuring as having a head over the 90th centile so that triggered a lot of concerns. My little boy however continued to grow (long bones on the small side) and I was told it would be ok as he would completely drop off the centiles if it was conditions they were questioning. I went to two NHS hospitals and received negative news, however paid for a private scan and all was fine there. I think the private clinics have better equipment. It was a horrible time! If you want to send anymore questions or messages feel free .

[1sttimerph]

Forgot to add my little boy was under the 5th centile for long bones.

[Trinity613]

I was in the same situation as you 17 weeks ago. The femur was on the 3rd percentile and the other measurements were around the 11-15th. I was sent to University College London for a more detailed scan which confirmed the measurements and was given a list of scenarios with the worst being a chromosomal abnormality and the best just a small baby. I was also advised to have an amniocentesis. Needless to say I was all over the place (especially since my other children were all quite big at birth and my husband and I are not short I’m 5’6 and hubby 6’4). I really didn’t want to do anything invasive and was told I could have a blood test which is very reliable to rule out trisomy. Unfortunately it is only offered privately and it costs around £400. My peace of mind was more important then money and I had it done the same day. Included in the price was a scan and the lady at the private clinic was adamant it was just a mistake at the 12 weeks scan and the baby looked totally fine. I also had a TORCH blood test to rule out any infections. Fast forward to now, I am 37 weeks and had a scan last week (have been having scans monthly and at the beginning even every fortnight). The baby is now on the 50th percentile for everything except her stomach measuring at the 80th!!! Please don’t do like me and worry sick. I almost had a nervous breakdown before receiving the results for the NIPT test and was constantly on the verge of crying. All that for nothing. I haven’t given birth yet but they seem to think that everything looks totally fine now. I know they do associate short femur with Downs but I have searched the internet extensively ( I love the medical field and always wanted to be a dr) and there very little evidence that there is a link with Down when the only soft marker is short femur and no other sign is found. I hope it helps and please don’t hesitate to ask me questions.

Wishing you a carefree end of pregnancy xx

[GBrown7 in reply to Trinity613]

Thank you so much for replying. Its really reasuring to hear someone having a positive outcome from this. We have had 4 years of trying and were just about to start IVF and i luckily fell pregnant naturally. This certainly hasnt been an easy ride so far!

I am trying not to get stressed because its not good for the baby but thats easier said than done. xx

[Trinity613 in reply to GBrown7]

I totally understand and was constantly told the same : don’t worry it will make things worse for your baby etc…

To be honest once all my results came back clear and the scans showed no anomalies, I started to relax and put it at the back of my mind. But 1 thing I would have liked to hear and wasn’t told was that it can change!! I asked the specialist sonographer at UCH if the baby could eventually catch up and she said no!! But clearly it isn’t true! Drs don’t know everything and very rarely admit their mistakes so don’t get too stressed by their pessimistic scenarios. Usually they envisage the worst when there was no reason to.

Were all the other measurements on the smaller side or bang in the middle?

Oh and btw on my last scan with a specialist sonographer when I asked how she explained such a jump in the measurements, she did admit that the femur being the smallest part to measure in a baby, is quite hard to get a reliable measurement…

[GBrown7 in reply to Trinity613]

Thank you. All my other measurements were 'normal' and where they should be. The femur meaurement was right on the line between 'normal' and 'small'. The midwife said previously they wouldnt have worried as its not in the small box , only on the line but now they have to refer you for further tests.

The baby was moving around lots whilst she was trying to scan me so i guess that could have made it harder to get an accurate measurment. xx

[Trinity613 in reply to GBrown7]

Oh so definitely I wouldn’t worry. During my 12 week scan the baby was constantly moving and after spending 30min trying to get the CRL measurement (which helps determine the due date) she actually told me: Im running really late and don’t have time anymore so I will take whatever measurement I have. It was obviously not reliable and because of her my whole pregnancy was overshadowed by a dark cloud. If your baby was very active like mine then the likelihood that the measurement was off is very likely. I’m sure your next scan will be reassuring. Did you get the combined screen test for down at 12 weeks? Just wondering why they offeref amniocentesis. In my case they offered because I had missed the test.

Please let us know how it goes xx

[GBrown7 in reply to Trinity613]

I had the blood test at 12 weeks to check for Downs and that came back as clear. According to the receptionist at The Rosie in Cambrige, although the bloods came back clear, the results arent 100% accurate and there is a small chance that the baby could have Downs. xx

[Trinity613 in reply to GBrown7]

Yes but they should have mentioned the NIPT blood test which is 99% accurate before encouraging you to go through with a procedure as invasive as an amniocentesis which carries a risk of miscarriage…

[GBrown7 in reply to Trinity613]

I guess the specialist will talk us through that tomorrow if further tests are needed. Id much rather a blood test than the amniocentesis. Bloody minefield!

[GBrown7 in reply to Trinity613]

just got home from hospital. Been re scanned and baby is perfectly fine and all measurements are where they should be. Femur is measuring 34.3 today! Sonographer thinks that the previous measurement taken on Friday was wrong and doesn’t think there is anything to worry about. She is going to sent my notes over to the hospital I’m under and doesn’t think there is any need for them to monitor me. Relieved doesn’t cut it!! Xx

[Trinity613 in reply to GBrown7]

Wow that’s great news!! Thanks for the update. Wishing you a peaceful and enjoyable rest of pregnancy xx

[Nelly1112]

My 1st babiea femur percentile was 7% at my 36 week scan and he is absolutely fine xx