Many parents choose to do so if the initial screening detects a higher risk of any abnormalities. You may choose to have fetal genetic diagnostic testing done after your initial screening. However, there is a higher risk of pregnancy loss with CVS. This test can be performed between 10 and 13 weeks of pregnancy, which is one advantage it has over amniocentesis.

Chorionic Villus Sampling (CVS) testing is conducted using a sample of the placental tissue.There is a very small chance of pregnancy loss because of amniocentesis Leakage of amniotic fluid and slight bleeding can occur after amniocentesis, but in most cases it stops on its own. This can also be used as a paternity test while pregnant. The fluid is then tested for genetic birth defects and abnormal chromosomes. A thin needle is inserted into the womb, and a small amount of the amniotic fluid that surrounds the fetus is removed under ultrasound surveillance. Amniocentesis is usually performed between 15 and 20 weeks of pregnancy.This test is not recommended for those pregnant with multiples. The test measures small fragments of fetal DNA in the mother's blood and can determine the chance of a chromosomal problem. Cell-free DNA screening may be performed from 10 weeks on through pregnancy.Sequential screening has a higher detection rate than individual screen results. The results are first reported after the first trimester sample has been submitted, and a final determination is made after the second trimester sample. Modified Sequential Screening is a combination of the first trimester and second trimester screening.Ultrasound at this point in the pregnancy can detect neural tube defects, anencephaly, congenital heart defects, renal agenesis, gastrointestinal defects, and other conditions. The International Society of Ultrasound in Obstetrics and Gynecology recommends performing an ultrasound between 18–22 weeks of pregnancy as part of routine prenatal care. Second trimester screening is performed between weeks 15 and 25 of pregnancy and includes a maternal blood test (a quad test or triple test depending on which state you live in) and ultrasound.The results of the blood test, ultrasound, maternal age, and gestational age of the fetus are then used to calculate the risk of genetic disorders like Down Syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13). First trimester combined screenings include ultrasound (nuchal translucency ultrasound measurements) and maternal blood test for PAPP-A and beta-hCG. First trimester combined screening is usually performed between weeks 10 and 13 of pregnancy.Screening tests will determine whether the fetus has a high risk for a certain condition. There are a couple of different types of genetic tests that are conducted during pregnancy.

Sequential testing pregnancy