By the ninth week of pregnancy, the embryo develops into a fetus . There are about 40 weeks to a typical pregnancy. These weeks are divided into three trimesters. What are the three stages of fetal development called? Fetal development is an orderly and intricate process. Track fetal development with our week-by-week growth chart. From 8 to 41 weeks, see how length and weight increase, reflecting your baby's growth and progress throughout the pregnancy. Human embryonic and fetal development is a fascinating journey that transforms a single cell into a fully formed fetus . This diagram illustrates the key stages from fertilization to 20 weeks of fetal development, providing a clear visual guide for understanding this process. Fetus , the unborn young of any vertebrate animal, particularly of a mammal, after it has attained the basic form and structure typical of its kind. A brief treatment of the fetus follows.
