Downsyndrome/gender blood work accurate?

[SujeyNRog]

Hi girls...
Im wondering if any of you have had the blood work testing for downsyndrome and gender. Well i am 16 weeks pregnant and two weeks ago i was performed a blood screening test .Every thing in the downsyndrome test came out normal thank god!! And they told me im having a boy.....and omg i cant believe it!!! I have three little girls at home ...im super exited i cried with joy....but to be honest im scared..how can they know with out seeing?..how effective are these tests? Please your opinon as a mother means alot to me..thanks in advance

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[Nikko88]

If you had a genetic screen, it's generally a yes/no result. There are some caveats about the procedure. But basically, if you are having a boy then they detect Y chromosomes in your fetal blood portion. I don't know the specific markers that they are looking for or how they isolate the fetal cells from the maternal cells. It would be exceedingly rare (although possible; my background is in genetics and developmental bio so I can go into more detail if you really want to know) to detect the presence of a Y chromosome and not have a boy.

ETA: WebMD gives the accuracy at 94.5% in the first trimester and 99% accurate at 20 weeks.

 

[laura_2010]

I had the Harmony test which I think maybe the same as you had?
Its pretty effective too - I found out I was having a Girl and no DS ect... and took around 2 weeks for a result xx

 

[SujeyNRog]

If you had a genetic screen, it's generally a yes/no result. There are some caveats about the procedure. But basically, if you are having a boy then they detect Y chromosomes in your fetal blood portion. I don't know the specific markers that they are looking for or how they isolate the fetal cells from the maternal cells. It would be exceedingly rare (although possible; my background is in genetics and developmental bio so I can go into more detail if you really want to know) to detect the presence of a Y chromosome and not have a boy.

ETA: WebMD gives the accuracy at 94.5% in the first trimester and 99% accurate at 20 weeks.

Ok now im confused what do you mean the presence if y and no boy?...

 

[SujeyNRog]

I had the Harmony test which I think maybe the same as you had?
Its pretty effective too - I found out I was having a Girl and no DS ect... and took around 2 weeks for a result xx

Idk what the test name is called the dr explained it was a rest for downsyndrome but we can also find out the gender....i had it done at 14 weeks

 

[Fizzyfefe]

Girls have 2 X chromosomes. Boys have one X and one Y chromosome. So if your test detected a Y chromosome, then it means you're having a boy. If no Y chromosome is detected, it means you're having a girl.

 

[Nikko88]

In very rare instances, some of the genes on the Y chromosome end up on the X chromosome. Depending on the markers used to detect the chromosome, you could fail to detect a Y chromosome or detect one and not have all the genes needed to make all the boy parts. But this is exceedingly rare. XY females (Swyer syndrome) occurrence varies but can be as low as 1 in 80,000 births. Genetics is fascinating.

 

[Mrs. MB]

We didn't do Harmony, in my doctor's practice that's offered to mother's over 35 and in high risk pregnancy. I know that's not the case with other practices as many of my friends had Harmony screens.

My doctor's office does a combined quad screen. First trimester blood test + 12 week ultrasound gives a preliminary result then second trimester blood test + 20 week ultrasound is combined with preliminary for a final result. The combined quad doesn't test for gender but is very accurate. Our baby girl came back screen negative for everything. We found out gender through ultrasound.