A grand mal is an ultrasound done between 20 and 24 weeks of pregnancy to see if the fetus is developing abnormally and thus to rule out malformations. The main purpose of the grand mal is to check whether the baby’s development in the womb is in accordance with the gestational week, whether the fetus is healthy, how well the limbs, mind and internal organs are developing, to rule out some congenital diseases but not 100%, and the usual condition of amniotic fluid and umbilical cord. It is recommended that pregnant women go to a qualified hospital for a major teratology examination to ensure the accuracy of the test results.