Antenatal Screening Results

I had a phone call today to tell me the results of my antenatal screening blood test, they told me I am low risk for Edwards and Pataus but that I am higher risk for Downs Syndrome, she said I was showing as a 1 in 5 chance, I was offered further screening either non evasive which is basically another blood test or invasive which would be a amniocentesis procedure which carries a chance of miscarriage, I have opted to have the blood test which is booked for Wednesday, has anyone else gone through anything similar? Trying to stay calm at this stage until we know anything further