The placenta is an organ that begins developing when the fertilized egg attaches to the uterine wall. It's unique in that it's only present during pregnancy. Though the placenta is fully formed and functioning by 12 weeks, it continues to grow throughout pregnancy.
The placenta also connects you and your baby through the umbilical cord. Together, the placenta and umbilical cord bring oxygen, nutrients, hormones, and immune protection from your body to your baby. These same structures also take waste away from your baby.
It is important to remember that medications, viruses, and other substances you take into your body can pass to your baby through the placental.
After your baby is born, the placenta separates from the uterine wall and exits your body as the afterbirth. If you have a c-section, your doctor removes the placenta surgically after the baby is delivered.