I agree with what Langkawi06 said. It is definitely a personal choice.
Ultimately, doctors will always give you the stats and the probabilities, however it does not mean is WILL happen. The 12 weeks tests provides the stats based on ages and blood result but not based on the actual individual case. 1:4 chance I was given (based on scans not age nor blood test) and the doctor was so sure my child had a problem that she informed me of my termination options on the same day...
Heck, 1 in 4 still means 75% chance that my baby is fine... and he is... If I had given in to the hype I would not be so blessed today. He is my pride and joy and I can't imagine life without him now.
MissJenOK, Congratulations! It is a journey of a lifetime.