oper cell division, there isn't a test yet to the likelihood of Down syndrome before conception (Exceptional children p173). One recent study noted that a rise in children born with Down syndrome between 1990 and 1995 because of the old maternal age. The age of the father does not seem to be a factor. When a woman becomes pregnant, there are screening tests that can be performed to detect Down syndrome beginning at the tenth week of gestation. Of course the test isn't 100% accurate so you should know a positive result does not mean Down syndrome is present and a normal screening doesn't mean the baby will be born without Down syndrome; the chance is just reduced. Its very important to know that some screening test may slightly increase the chance of a miscarriage. Tests in utero for identifying Down syndrome include amniocentesis, which is a needle inserted into the uterus and a sample of the amniotic fluid surrounding the fetus is taken out. Usually used within 14-16 week of pregnancy. This test is 99% accurate, but carries a 0.5 percent chance of miscarriage. Chorionic villus sampling (C.V.S.) is used by taking cells from the placenta through the mother's abdominal wall or cervix. Performed between tenth and twelfth week of pregnancy, this test is 98 percent accurate and carries a risk of limb deformities and a one to two percent chance of a miscarriage. Karyotyping can be used through the process in which a picture of chromosomal patterns is prepared (Genetic Disorders.p5). An ultrasound can identify any traits a fetus has such as shortened thighbones or gastrointestinal blockage that can be associated with Down syndrome, but not as accurate to be used

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