Avatar universal

Prenatal paternity test

Hi! I was wondering if old DNA from a previous miscarriage or birth can false results for a prenatal paternity test?
2 Responses
Sort by: Helpful Oldest Newest
134578 tn?1614729226
Hi, Sheldon, from what I remember, your prenatal DNA test from Ravgen said the father is your boyfriend; that he got positively identified. Are you saying you had a recent miscarriage or birth from this boyfriend, and immediately got pregnant again, and wonder if the second pregnancy is from the other guy but that the test only picked up DNA from the earlier pregnancy?

First, did you have a recent miscarriage or birth (with your boyfriend the father) before you got pregnant this time? In the scenario you just proposed, with the wrong guy the father, how do you explain away the fact that the testing lab didn't find the wrong guy's DNA? (Why would the DNA from the present pregnancy not show up?)
Helpful - 0
Yes i had a recent miscarriage 7 months before getting pregnant again. So I was wondering if the old DNA from the baby could  still be in my bloodstream and that’s what DNA they picked up for this pregnancy
Or if old DNA disappears straight away??...
You could call the DNA testing lab and ask. I don't think it would stick around in your bloodstream to such an extent (if it was traceable at all by the time seven months had passed) that it would somehow blot out all the traces of the live, new pregnancy that is filling your bloodstream with its DNA.
Basically, I can't see this idea (an old miscarriage blocking out the evidence of a current pregnancy) as a real possibility. DNA evidence of the old pregnancy would be faint compared to the new, or absent. If they did find evidence from the past pregnancy they would have found lots more from the current pregnancy. And they would not have given you a positive for the guy they gave a positive for, they would have told you the past one (faintly visible if at all) was from him but the current one was not from the same father. If they could even detect the earlier one, you would have been told you had two babies from different fathers.

But it just doesn't seem like something from that long ago would have anywhere near the same signalling power (if any) in your blood as an existing pregnancy does.  It's delicate enough work for a prenatal test to find DNA from the existing baby.
I have been looking at medical sites to see if I can find any information on this. Pretty much every site says that previous pregnancies or miscarriage would not affect any prenatal test except one site that says that it could...
I was just wondering if my prenatal paternity test would of picked up old DNA from when I was pregnant with my boyfriend and so they couldn’t detect the new DNA from the guy I cheated on and that it could of gave me a false positive.
From my previous posts I had sex with a guy that had a vasectomy and I got a prenatal paternity test to rule him out.
134578 tn?1614729226
If it "would of picked up old DNA from when I was pregnant with my boyfriend" -- that would be unlikely because the baby was long gone, and if anything is left in your bloodstream it would be just bare traces, if that.  

"and so they couldn’t detect the new DNA from the guy I cheated [with]" -- if a test is good enough to detect old traces from a miscarriage (and nobody is saying it is), how could it not detect a great deal more current DNA from a current pregnancy that is in your body right now? There is no logic to this link in your reasoning chain.

"and that it could of gave me a false positive" -- but where would be the positive for the guy who is the present father of the current pregnancy, in this scenario? It's not like a DNA test looks at one marker and tells you who the dad is. It looks for 23 pairs, and can tell if there are markers from more than one dad in the bloodstream.

Sheldon, you should rethink what is the real cause of your anxiety. As I often tell women who are obsessing in the face of medical evidence, identify the real root of your anxiety (I can guarantee you that deep down, it's not worry about who is the dad), and work on that., and the straw-man issue of paternity will die away.
Helpful - 0
Have an Answer?

You are reading content posted in the DNA / Paternity Community

Top Pregnancy Answerers
13167 tn?1327194124
Austin, TX
4769306 tn?1568490209
Learn About Top Answerers
Didn't find the answer you were looking for?
Ask a question
Popular Resources
Get information and tips on how to help you choose the right place to deliver your baby.
Get the facts on how twins and multiples are formed and your chance of carrying more than one baby at a time.
Learn about the risks and benefits of circumcision.
What to expect during the first hours after delivery.
Learn about early screening and test options for your pregnancy.
Learn about testing and treatment for GBS bacterium.