Title: Prenatal Development | Introduction to Psychology
Headings: Prenatal Development
Prenatal Development
Learning Objectives
Prenatal Development
Germinal Stage (Weeks 1–2)
Embryonic Stage (Weeks 3–8)
Fetal Stage (Weeks 9–40)
Prenatal Influences
What Do You Think? Should Women Who Use Drugs During Pregnancy Be Arrested and Jailed?
Infancy
Link to Learning
Think It Over
Glossary

Content: Now blood vessels grow, forming the placenta. The placenta is a structure connected to the uterus that provides nourishment and oxygen from the mother to the developing embryo via the umbilical cord. Basic structures of the embryo start to develop into areas that will become the head, chest, and abdomen. During the embryonic stage, the heart begins to beat and organs form and begin to function. The neural tube forms along the back of the embryo, developing into the spinal cord and brain. Fetal Stage (Weeks 9–40)
When the organism is about nine weeks old, the embryo is called a fetus. At this stage, the fetus is about the size of a kidney bean and begins to take on the recognizable form of a human being as the “tail” begins to disappear. From 9–12 weeks, the sex organs begin to differentiate. At about 16 weeks, the fetus is approximately 4.5 inches long. Fingers and toes are fully developed, and fingerprints are visible.