The statement that the greatest risk of forming birth defects and miscarriage occur in the fetal stage is false.The greatest risk of forming birth defects and miscarriage occurs in the first three months of the pregnancy, when the organs of the baby are forming. The fetal stage on the other hand begins after the tenth week of pregnancy and the developing child is no more call embryo. However, till now many important processes are started: the process of developing heart and nervous tissue , developing a gastrointestinal tract , distinguishable limbs.