The document provides information about the stages of pregnancy from fertilization through birth. It describes how sperm travel through the reproductive system and can fertilize an egg within 2 days of intercourse. If fertilization is successful, the embryo will implant in the fallopian tube and begin developing, with major organ systems forming in the first trimester as the embryo grows to be 1 inch long by 12 weeks. Ultrasounds are performed during each trimester to monitor fetal growth and check for abnormalities. By 40 weeks, a full term baby is typically 21 inches long and weighs around 7 pounds at birth, which usually occurs through either vaginal delivery or C-section.