1) Does that the fact that I already have 2 children 'reduce' the risk of having a Down's syndrome child?
2) How high is this risk? i.e.what percentage of women age 45 and over have Down's syndrome children.
1) No, that doesn't make a difference to the risk.
2) The statistics show there is a 1 in 30 change if the pregnancy goes to term but higher before that as many abnormal pregnancies will miscarry or be terminated.