Hello, I've just had 12-week screening for Down's Syndrome. I'm pregnant with twins from donor eggs. I think my hospital may have calculated my twins' risk factor incorrectly. Here are my stats:

Age of biological mother: 22
Nuchal fold at 12 weeks: twin 1: 1.3mm
twin 2: 1.5mm
Blood test: HCG: 5.8 MOM
PAPP: 0.49

Risk factors: nuchal: twin 1: 1/7000
twin 2: 1/6000
bloods: 1/30
combined risk (the factor I'd like to be checked if poss): twin 1: 1/153
twin 2: 1/134

EC: 12th July 2010
ET: 13th July 2010
Date of 12-week scan: 21st Sept 2010

I used an online risk factor calculator and my results were much more positive. I'd be really grateful if you could look at these results to see if the combined risk factor is correct. I'm so worried.

Many thanks!