-
germinal stage
First and shortest stage of prenatal period. Methodical cell division and attachment of organism to uterus take place during this period. -
embryonic stage
The zygote is now an embryo. Embryo develops 3 layers- the Ectoderm (skin, sense organs, brain, spinal cord), the Endoderm (digestive system, liver, respiratory system), and the Mesoderm (muscles, blood, circulatory system). At end of embryonic stage, embryo is 1 in long. -
Fetal stage
Individual is now called a fetus. This stage starts when differentiation of the major organs has occurred. The fetal stage starts at 8 weeks and continues until birth. -
Full term
The average size newborn is 7.5 pounds and 20 inches long. At this point, most of the vernix is gone, 15% of the body is fat and the chest sticks out. Hair on the baby's head is now coarser and thicker. The lungs are mature. At birth the placenta detaches from the uterus and the umbilical cord will be cut as the baby takes his first breaths of air.
