What are the odds of having a child with downs syndrome in the u.S., if you do all the appropriate screenings?

Age dependent. One fourth of pregnancies that are affected by downs are either stillborn or miscarried, that said, one of the greatest variables is maternal age at conception. If you are 20 years old the risk is roughly 1 in 1600, if you are 35 the risk is about 1 in 380 and if you are 40 it is about 1 in 106.