@ttcy3 do you know which test brand you took? I did the MaterniT21 plus test and i don't think i saw anywhere where it listed 'fetal fraction'. But very interesting and good to know! My OB also just told me that technically the Cell free DNA test was only tested in women over 35 years...so technically when used in women below that age (as I was with my first 2 pregnancies) the results are 'not as accurate'. All very confusing...
@emeraldisle17 I did mine with Unity. My friend thought Harmony (before sold by roche) and MaterniT21 were both good companies. Natera was questionable because of their lack of transparency with their algorithm.
@ttcy3 do you know which test brand you took? I did the MaterniT21 plus test and i don't think i saw anywhere where it listed 'fetal fraction'. But very interesting and good to know! My OB also just told me that technically the Cell free DNA test was only tested in women over 35 years...so technically when used in women below that age (as I was with my first 2 pregnancies) the results are 'not as accurate'. All very confusing...
I did MaterniT21 as well and the fetal fraction is towards the beginning of the report. I think like 3rd line or so.
@emeraldisle17 there is actually data on under 35/low-risk pregnancies and cffDNA testing! It’s more likely to give a false positive if you’re low risk, which is also true of any screening tool. If you’re over 35/high-risk, a positive result is very predictive of a chromosomal abnormality, especially T21/Downs syndrome. If you’re under 35/low-risk, a positive result is a less reliable predictor of a chromosomal abnormality (I’ve seen about 60%), with less reliability for T13 and and T18. A negative result is very predictive for anyone.
Why that’s true is because the rate of false positives is the same for everyone, but the rate of true positives is much higher if you’re over 35, so the proportion of total positives that are “real” is much higher over 35.
Bottom line: if your result is negative (and passes all quality assessment criteria), you can be very confident that everything is fine, chromosomally-speaking, regardless of your age. If it’s positive, talk to your provider about testing to verify, ESPECIALLY if you’re under 35, before you make any permanent decisions.
@ttc3y I hope that helped you a little. I should also say that the paper I found was several years old, so there may be more recent tweaking to cutoffs and algorithms that improves accuracy. Either way, talk to your midwife about the accuracy and whether there’s additional testing you should consider. They should have said “inconclusive” if there wasn’t enough fetal DNA to perform the test accurately, but it’s always worth asking questions.
@fertile-turtle I found a research paper indicating that the fetal fraction should be between 2-4%. From my friend’s experience working with prenatal testing, the companies are not being transparent with their algorithms. I think Unity should have put inconclusive.
Honestly, I’m not too worried. We did genetic testing with our embryos before transfer and all 23 chromosomes were checked out to be fine and normal. Part of me didn’t feel like the NIPT was necessary since the genetic testing was already done but I suspect that my fertility clinic didn’t pass on those results to my new midwife properly. I figured insurance would cover it since I qualify with my age.
My OB called today to let me know that all results came back low risk/normal. I opted to wait on what the fetal sex is because we’re going to do a tiny little reveal at home with just our boys, just as a fun way to get them involved. So I need to wait until the results are on the Natera portal to email them to a friend whose helping to coordinate. How long did it take for your results to be uploaded after the OB received them
@kristinl492 Mine were available next day on Natera after released by my OBs office.
Me: 34 DH: 34 Married 10/28/17 Our TTC Journey
TTC #1 February '18 Team Green turned TeamBlue 10/15/18
TTC #2 January '21 BFP June '21 MMC/Blighted Ovum that led to D&C July '21 Jan '22 - started IF testing BFP Jan '22 MMC/Blighted Ovum that led to D&C Feb '22 BFP May '22
Just got my results back after the “higher chance” result of 1 in 122 from the NT. ALL CLEAR! Feeling very grateful and still getting my head around it. So glad we have this modern technology.
At 35 years old and pregnant with my first I was so nervous for my Panorama NIPT results. Just got them back this morning and low risk with a 9.9 fetal fraction! My heart is feeling so grateful and happy right now. I can’t even describe it. 🙏🏼❤️
Re: NIPT Results
Why that’s true is because the rate of false positives is the same for everyone, but the rate of true positives is much higher if you’re over 35, so the proportion of total positives that are “real” is much higher over 35.
Married 10/28/17
Our TTC Journey
Team Green turned Team Blue 10/15/18
TTC #2 January '21
BFP June '21
MMC/Blighted Ovum that led to D&C July '21
Jan '22 - started IF testing
BFP Jan '22
MMC/Blighted Ovum that led to D&C Feb '22
BFP May '22