Chromosomal abnormalities of the fetus are not common. But there are many tests to diagnose such fetal abnormalities at an early stage of pregnancy. Chromosomal abnormalities result in more than 50% of miscarriages in the early stages of pregnancy. The most usual type of chromosomal abnormality is Down's syndrome. This causes low IQ, short limbs, heart problems at the time of birth and a wrinkle around the eyes. Other less common syndromes are the Patau's syndrome and Edward's syndrome. Molar pregnancy is a rare form of pregnancy where there is an abnormal composition of chromosomes. A molar pregnancy test is prescribed by a gynaecologist in the case of need. This test is done using repetitive tests of urine samples to make sure that the hCG is disappearing. Although chromosomal abnormality screening treatments are not possible, there is a choice of early detection using the screening tests available and further upon discontinuing the pregnancy. Women with abnormal pregnancy symptoms and those with uterine abnormalities may have to take these screening tests. Maternal Blood Screening detects cases with above average risk of birth defects. AFP screening is the most common test for such chromosomal abnormalities and if the AFP level is higher or lower than normal, the fetus may have a neural tube defect or Down's syndrome. Triple screen, Quad screen, Ultrasound and Chorionic villus sampling are other screening tests.