So, your physician needs to refer you to us to have an ultrasound and evaluation between 11 and about 13 weeks gestation. We first perform the ultrasound, which includes evaluation of the fetus, and also evaluation of the blood flow in the maternal uterine arteries. After that, a nurse will ask you a number of questions about your history, and check your weight and height, and she will also evaluate your blood pressure. After this, you will also have a blood sample drawn, and all of this information will be sent to a laboratory that combines all of these factors and gives us a specific risk for you individually.