How early can you take a blood pregnancy test and it be accurate?

About 2 weeks after intercourse it should show up.

blood test is the best test.

i waited untill i missed my whole period then the day after i used a clear blue pregnancy test witch did say positive thats when i went to hospital and they done me a blood test good luck i’m now 5 weeks preg good luck

I was only pregnant three weeks when I got my positive result in a blood test.

Just depends on how much HCG the pregnancy is putting out, every one is different. I have actually heard of them coming back as positive before the fertilized egg had even implanted in the uterus, but that is rare. I would say to wait at least 7-10 days after conception so that the egg would be implanted for sure and have enough time to start increasing the HCG.