28 weeks and very worried

[Veryworried2023]

I am 41 years old and 28 weeks pregnant. The pregnancy was unplanned, a huge shock and has been very difficult. This has been largely due to worries about my age and the risk of abnormalities.

I paid to have a private NIPT (Harmony) when I was about 11 weeks. It gave a low risk result. (There is no first trimester screening offered to public patients in the country I live in.) I would have ended the pregnancy if I knew there was a problem.

I was still worried about my age and asked for an amniocentesis. I wasn’t able to talk to anyone from fetal medicine until I was 22 weeks. They gave me the anatomy scan and after speaking to them I decided not to go ahead with the amniocentesis.

I am now feeling extremely worried. I saw on my file today that at the anatomy scan at 22 weeks the femur length was on a much lower centile than the biparietal diameter which seems like a bad sign for Trisomy 21. Also the femur length had gone down a lot proportionally and on the centiles since an earlier scan at 18 weeks.

I have also since read about many cases of false negatives from NIPT on this site and elsewhere. I’ve also seen that my fetal fraction was low at 5% which I think reduces the accuracy. I now understand that there is a 1 in 100 chance of me having had a false negative so I am no longer feeling reassured by the NIPT, especially because the likelihood of T21 is so high based on my age.

I feel like I can’t cope with how worried I am and I don’t know what I can do. I deeply regret not having had the amniocentesis as the NIPT result seems next to useless at this stage. (Please just don’t respond if you are going to be harsh as I feel on the verge of breaking down.)

Presumably if you're only now reading this from your notes then no concerns have been raised with you from any of the scans, even those performed by the very experienced professionals in fetal medicine. I really do think you need to take this as reassurance- if they were worried by the femur length or anything else they had seen they would be sharing this with you and encouraging you to have the amniocentesis. Instead they actively discouraged you, suggesting that from their observations and in their very experienced opinion the risk of the procedure was greater than the risks of your baby having T21.

It sounds like your head has been spinning since you found out you were pregnant and I wonder if you might benefit from talking through your anxiety with a health professional. Having a baby is a worrying time and whilst the risks are of course greater with age, many many 'older' women have perfectly healthy pregnancies and babies and there is nothing to suggest you won't be the same. And then there's the fact that there are still loads of things to worry about and fixate on even once your baby has arrived in the world so it's good to get a handle on the anxiety because otherwise it's endless worry and stress.

Try to relax, trust in the professionals and enjoy the last few weeks of your pregnancy as this may be the only time you ever experience it.

Hi @Veryworried2023 i am also 28 weeks almost and am under foetal medicine after a high NT measurement (4mm) at 12 weeks and a 1 in 2 chance of Down syndrome (I’m 38). My NIPT came back low chance too but I can totally empathise with the anxiety you have, I study every scan report at length each time and have worried myself sick throughout the pregnancy that something is wrong. I declined amniocentesis earlier in the pregnancy as all scans looked normal and my extended NIPt was low chance. at the time it just didn’t feel like a proportionate risk to take given the low chance nipt and lack of any markers at all for anything - and I also have a lot of experience of being in the 1% of stuff being wrong in pregnancy - I thought amnio would be no different and I would be the 0.5-1% of people who miscarry. But have to say the anxiety of not knowing is intolerable at times and I wish I had more certainty.
HOWEVER, what I will say is that foetal medicine are very, very transparent and direct. The midwife there has assured me after every scan that, had the consultant seen anything on a scan - any tiny little question mark, however small or seemingly insignificant - they would discuss it with me. A friend of mine was also under a different foetal medicine dept for different issues a few years ago and she said similar, they left no stone unturned and were beyond thorough and actually very directive to the point of blunt about the prognosis etc. I can totally empathise with you but they are experts in their field and, if anything, I find them a bit doom and gloom and very very careful not to give any reassurance whatsoever in case they are wrong. If they haven’t said anything is wrong, I would try to trust them. They are super cautious and I really do think they would say if they had concerns.
In terms of false negative NiPTs, they do happen but they are rare. Your result is far more likely to be correct than incorrect. I realise there are 1 or 2 stories on here where this has unfortunately happened but there are thousands of women taking the NIPT every day and the chances of it being incorrect are pretty slim. In terms of foetal fraction, mine was 6.2% which I was told by the clinic was fine - My understanding is that, as long as the foetal fraction was high enough to perform the test (usually 4+), a higher foetal fraction doesn’t offer more reassurance (it doesn’t work like that) - so 5% is plenty to get what they need. In fact, a very high foetal fraction can be an indicator for T21 according to some stuff I’ve read. Where did you get the stat that there is a 1 in 100 chance of you having a false negative?

Being “older” does give you a higher background risk than someone in their 20s but, in reality, babies with DS can be born to anyone. It sounds as though there have been no indicators at all in your pregnancy that anything is wrong - eg I’m younger than you (albeit still an “older” mum) and I have had more indicators than you,
your pregnancy sounds pretty straightforward aside from your anxiety about your age (apologies if this isn’t the case and there have been complications that you haven’t mentioned). Anecdotal evidence of course but I know plenty of women in their 40s who have had babies with no chromosomal abnormalities.

I plan to have the amnio at 32 weeks. It is very late in the day to do anything with any bad news we may get from that but I want
to do it so that I have a bit more certainty before the birth. Is this something you would consider?

I’m the same age as you and I did lots of research - even at our age chance of t21 is 1 in 100 so you have a 99% chance of not having it! Re femur length, agree they would say if they were concerned and also they look at lower than 5% as what they worry about. Also my obstetrician said to me last week not to look too much at growth % on the anomaly scan (which I was doing) as they will look at the % more later on. I’m 21 weeks.

I have a different situation to you but understand the worry: I had a more than 1 in 2 chance of t21, a high chance nipt, an abnormal cvs and then against all expectations a normal amnio… they think abnormalities are confined to the placenta but being closely monitored. I think your low chance nipt is very reassuring. I still have many worries about how mine will turn out but people have also given me good advice which is trust the doctors if they say scan looks ok and don’t read into the numbers too much as they will tell you otherwise. I know from unfortunate experience that when they are worried about something they will talk to you in grave tones and tell you if it’s unlikely to turn out well. Agree with the above that they definitely don’t give false reassurance - they basically told me there was no chance of a normal amnio result and here I am!

hope you find that helpful, it’s hard with all the worries pregnancy brings! X

I wanted to come back and say thank you for your kind and thoughtful replies. I have been so on edge that I felt I couldn’t reply. I am now 32 weeks and I have accepted that there is nothing I can do at this point so I will just have to see what happens when I give birth. I do regret not having more testing earlier but anxiety would probably still be a problem and this is where I am now. I wish those of you who are having amniocentesis tests around now the best and hope everything goes smoothly.