During sexual intercourse, millions of sperm go into the vagina. Only 1 sperm will penetrate and fertilize the female egg while it is in the Fallopian tube. One week later, the fertilized egg implants into the wall of the uterus. An embryo begins to develop into a baby. At 6 to 8 weeks, the eyes and face are formed and the heartbeat can be seen on ultrasound. At the end of 12 weeks (first trimester), all the baby's organs are formed. Now that you are pregnant, you will want to do everything you can to have a healthy baby. Two of the most important things are to get good prenatal care and follow your caregiver's instructions. Prenatal care is all the medical care you receive before the baby's birth. It is given to prevent, find, and treat problems during the pregnancy and childbirth.