A sinusoidal pattern on a fetal heart rate tracing indicates severe anemia of the fetus, like that which occurs in Rh-incompatibility. Therefore, a knowledge of the maternal blood type and that of previous children is most helpful in determining the cause of the sinusoidal pattern. The amniotic fluid index can help determine the likelihood of the patient experiencing cord compression, which would result in late decelerations. Late decelerations may also be caused by low blood pressure in the mother. Liver function test and complete blood count helps to diagnose HELLP syndrome in the pregnant woman.