13 week NT scan showed measurement of 3.6mm. Donor egg pregnancy.

[loulamay]

Had our 12-week scan yesterday - baby measuring 12w6d so I'm actually almost 13 weeks and the scan was then just because of how Christmas dates fell.

The sonographer said everything looked exactly as she would expect for this time of gestation - everything was in the right place and heartbeat strong, except for the NT measurement which was 3.6mm. We're in the UK where their cut-off is 3.5mm. We are waiting on NIPT results and a referral for a CVS test.
I am 44 and we've been through hellish years of IVF - we have a daughter who was a PGT-A tested euploid embryo but in our pursuit of a sibling, despite 4 more rounds of IVF where I developed OHSS and nearly died because of an ovarian torsion, we only produced aneuploid embryos - no doubt due to my age. We moved on to donor eggs and had a failed transfer, followed by this pregnancy. Our donor was 26 at the age of donation and was screened as per HFEA guidelines for a lot of genetic disorders or being a carrier for things such as cystic fibrosis.

We are really surprised by the NT result given the use of a young donor's eggs. We didn't get the embryos PGT-A tested mainly because of her age. With some research, I found the following statistical likelihood of the main chromosomal issues for that age, (and my husband's):

The risk of chromosomal abnormalities is influenced by maternal and paternal age. Here’s an estimate for a 26-year-old mother and a 44-year-old father:
1. Down Syndrome (Trisomy 21): The maternal age risk at 26 is about 1 in 1,300 (0.08%), but the father’s age may slightly increase this.
2. Edwards Syndrome (Trisomy 18): The risk is about 1 in 4,000 (0.025%).
3. Turner Syndrome (45,X): The risk is low and unrelated to paternal age, around 1 in 2,500 (0.04%).
4. Patau Syndrome (Trisomy 13): The risk is about 1 in 8,000 (0.0125%).

This may point towards the NT scan being linked to structural or cardiovascular?

I also found these studies to be interesting:
https://pubmed.ncbi.nlm.nih.gov/25305408/ - links exogenous progesterone to elevated NT fluid. I have been on high doses of progesterone since embryo transfer to 12 weeks.

https://www.jogc.com/article/S1701-2163(16)34121-4/pdf#:~:text=Women%20with%20a%20risk%20greater,1%3A150%20for%20trisomy%2018.- a Canadian study that breaks down NT results by age and CRL, and given that we are in the age range for a 26-year-old, and CRL was 66.3, the maximum cut off presented is actually 3.8mm rather than the 3.5mm of the NHS.

Several studies suggesting that NT results are higher in ART pregnancies - https://pubmed.ncbi.nlm.nih.gov/26138364/

I would welcome any opinions (and positive stories!!), especially if you are aged below 30 and have had an elevated NT measurement, or have been through similar with an IVF or DE pregnancy. We are devastated at the prospect of something going wrong, especially after everything it has taken to get to this point.

Thank you for reading.

My sisters nt was the same in her last pregnancy she is 37.

she declined any further testing ,so went through whole pregnancy not knowing for sure ,

my nephew was born in July and doesn't have ds .

It is only just over the upper limit of 3.5mm, I wouldn’t panic. I had a NT of 3.8mm and 1:30 chance of downs when I was 30. Ds is 4 and totally fine. Are you having a cvs or more detailed anatomy scan at fetal medicine?

Thank you both! We are in the Lake District so scan was at the local hospital and they have put in a referral for Newcastle for the CVS as apparently they have better equipment - hoping to hear something tomorrow or Friday about a date. Meanwhile, we will wait for the NIPT results which they took bloods for yesterday.

Just to add, I had the nipt too and was told if the results were low risk they would not advise cvs due to the risk of miscarriage and with being only just over the NT upper limit. Conversely, I was offered a cvs immediately last month when I had an NT of 12mm with a subsequent pregnancy. Fingers crossed for you.

Given how close to the "cut off" it is, try not to worry. Despite measuring down to the mm the scans aren't 100% accurate. With my youngest the scans showed his head measurement as literally off the scale it was (supposedly) so big. I was concerned about it and asked the consultant who said that there was a 15% margin of error in the scans. I was past the 20 week mark mind you, but they aren't 100% accurate and you've done everything that you can. Fingers crossed for you OP and best of luck.

Hey, I'm sorry things are stressful at the moment. Any changes to the usual routine is a worry, and I can only imagine that when you've been as much as you have it's even more so.

I don't have specific experience in regards to the IVF, I'm an older mum who had a high chance result in my second pregnancy. However you may be reassured given that you're only 1mm over the measurement, but there's always a chance of DS or other chromosomal differences regardless of age. I'm guessing you've not yet had the results of your bloods yet - this might change your view too. It can depend on area but hopefully you'll be offered the NIPT if your bloods return a higher chance of a chromosomal difference. NIPT is non-invasive and of no risk to your unborn child, as I'm sure you're aware. I never had the invasive tests as I was afraid of the miscarriage risks but that's a very personal choice, it depends how badly you need a 100% answer.

The other thing to think about is that a diagnosis of DS isn't necessarily a bad thing. Plenty of babies and children with DS are healthy and happy, and it's certainly not a death sentence or even a life-limiting condition as it was in the past. If you do end up with a high chance of DS there's a group which found really helpful when I was pregnant, www.facebook.com/share/g/15sGtbDUK7/?mibextid=wwXIfr

Lots of luck to you; it sounds as though you're doing lots of research and informing yourself well, which is great. Wishing you a speedy result and a smooth journey for the rest of your pregnancy. Always happy to chat/answer questions if that helps xx

@anicecuppateaa I'm so sorry about your subsequent pregnancy. Are things ok?

@thejadefish agree about the margin of error and that definitely helps given how close we are to the lower end of the range here.

thank you @Lulumamabear - we've already had bloods taken for the NIPT test which was offered on the same day as the scan, so hoping for results back next week!

Hoping the results come through quickly for you, it's an agonising wait xx

Thanks for asking, and I don’t want to derail your thread. I had a tfmr just before xmas and waiting for genetics results, but the baby was clearly very poorly. (Not to scare you though, that was a widely high NT and I have every hope your situation with be like my first time. My 4 year old is totally healthy).

@anicecuppateaa not derailing at all and I'm so very sorry for your loss. Thank you for sharing and for your other replies xxx

@loulamay i just wanted to offer you some reassurance. I was in this position back in August with an NT of 4.0mm. Completely turned our lives upside down.
we had a CVS and every test came back with completely normal chromosomes. Then two very detailed scans at 18 and 21 weeks with a fetal medicine consultant. Again everything was completely normal. We were discharged from fetal medicine and placed back on the low risk pathway. I’m now 33 weeks and baby seems to be completely fine.
A raised NT can mean something but it can also be a normal variation for some babies. The odds are more in your favour (I think we were quoted 70% chance of no issues with NT between 3.5 and 4.0mm).
I know how difficult and uncertain the waiting is so I’m happy to chat with you about any of this. Best of luck x

I had a very raised NT result....I can't even remember what it was now but it was something like 6.3mm! So the odds were high that something was wrong. Ruled out DS from an NIPT test but, to cut a long story short, after birth we discovered she had some mild cardiac issues which have never needed any treatment and it has healed itself as she has grown. And a bowel condition, which is life-long but I would obviously rather she didn't have it but gosh...lots of people have bowel issues these days. She had genetic and chromosome testing after birth and that all came back clear.

I think everyone just assumed it was something chromosome related with such a high NT but my daughter is proof that even scarily high NT can sometimes not mean that. I don't know if that helps to hear or not.

@starrynight009 it does, thank you for sharing!

UPDATE: bloods came back as low risk for T21, 1:493 and very low risk for T18 and 13, 1:5000. Went ahead with the CVS in any case because we wanted certainty and got results back today that are negative for all three! Massive hurdle to have overcome. So now we have the rest of the array that will come back in 2 weeks and a fetal echocardiogram in about 2 weeks as well. Fingers crossed...

Another quick update, in case anyone comes across these posts in the future and wants more information, as I did! Rest of the CVS array testing also came back as totally normal. So just the fetal echo to go and then hopefully we'll be in the clear.

Hello, I’ve just come across your post this evening. I have use had my 12 week scan after a round of ivf with donor eggs. I opted to have the test for Down syndrome. However I haven’t been provided with the donor egg age and so the hospital don’t think they can do the test. How did you find out the age of your egg donor? X

Hi @Smileychar it was part of the full profile we got when we chose her. Could you ask your clinic? Was it a UK clinic?

Is it the NIPT test you’re wanting to do or just the combined screening?

Hi @loulamay

we used a clinic within the UK. But we were provided an age range. I’ve sent them a message asking for an age and explained the situation. This is for the combined screening at the hospital. I’ve been looking at NIPT tests, and I don’t think the donor age is required, so I’m thinking of booking a test privately to save anymore delay x

Fingers crossed they can let you know! But if you can afford private then I would totally understand that route. IVF is just waiting upon waiting upon waiting so anything you can do to speed it up is always good.

Also, congratulations! how was first trimester?

I decided to book a private test as I didn’t want to keep waiting like you said, also I feel it may take some time to get the donor age of this is something they don’t usually do.
I have felt very rough in the first trimester, never sick but always so nauseous and tired.

how are you doing? It sounds like you’ve been through a journey! X

That's great - I hope you get the answers you need :-)

Yes, we've been through a lot, like so many people on here. IVF is brutal. Hoping for good news from our heart scan on Thursday and then I can relax. x

One final update in that the fetal echo all looked great. They want me to go back at 22 weeks just in case there are any small holes that weren't showing up, but to be honest that was the least of my worries! Just wanted to add, for anyone that might come across this post in the future and was in a similar situation.

Thank you to everyone who commented.

@Smileychar how did you get on?