Confused Downs Test

[Littlelou1508]

Hello Currently pregnant with my 2nd baby, went for my 1st scan at 14 weeks but was told baby was too big for measurements so decided to have a blood test due to my age, 38, the results came back as ....

*Not at Increased risk
Risk of Downs by maternal age 1 in 158
Risk of Downs by screen at term 1 in 468

Now 1st baby (had at 36) had both scan measurements (12 weeks) and bloods and he came back as 1 in 6000!

Now im scared as 2nd baby seems to be a bigger risk?

The risk factor takes your age into account, so the same result in your bloods gives you a higher risk on your late 30s than your late twenties.

The results of my last screen at 41 gave my baby a 1 in 9 risk of Down's (ie.
high risk) . Had I had those very same results in my twenties, the risk would have been low.

Towards the end of your thirties, the results/risk curve gets quite steep, so this could explain why your risk suddenly seems so much higher. My first screen at 37 was a 1 in 0000 result, yet four years later, my third screen was at 1 in 9.

Both babies were fine, BTW. But if you are concerned, you could consider paying for a private nipt blood test.

It can vary. I had a 1 in thousands and a 1 in 156 five years later. Both low risk and no further tests necessary.

Age, position of the baby etc can all have an effect.

Hi OP. I would say that the risk quoted is of limited value anyway because they've not included any measurements, but overall as long as the baby looked OK on the scan then this is good news, because your bloods must be pretty good if they've brought your background risk down to that extent.

FWIW I had a second trimester loss due to chromosomal abnormalities and am now pg again, 30 weeks now, and at my combined screening I cried with relief at being given odds of 1:358 for DS.

Good luck OP, it all sounds good to me.

Someone I know had a high risk and her lo didn't have down syndrome so don't worry too much! (I know it's hard)

Not sure what they've quoted the but it sounds to me what they may have given you your risk by age alone and then the risk after they've done the test. If so the test has shown you're lower risk than the average woman your age, so it's a good result. Here they don't give you the numbers just high or low risk.

I had a one in 5 risk from bloods ...twice!! Try not to worry.

We got a 1:72 results after blood tests only (was measuring 14+2 so "too late" for NT), I asked the nurse at the time if this could make the results any less accurate and she said no - the midwives at feto-maternal medicine later told me it would, and that bloods are only about 75% accurate anyway. Nobody has been able to tell me why our result came out as it did - doctor didn't have normal ranges to compare PAPP-A and HCG to, said it was most likely my age (36); midwife at 16 week check said that a number of variables (age, height, weight, blood results) go into an algorithm and that produces the result.

Not saying this to knock the support I've received - we decided to go for further tests (which have all come back normal) and the speed and supportiveness of our trust has been amazing. However, if I'd known beforehand that the screening test had this margin for error I might not have worried so much!

The results you've been given are low risk OP - agree with PPs that you should try not to worry.