For the nine months of pregnancy, the placenta serves an essential role in the survival of the fetus. Once the baby is born into the world the placenta is then expelled from the body and is no longer needed. It is the only organ in the human body that does this.
Unlike born humans, the fetal circulatory system works differently because the lungs of the fetus are not used for breathing while in the mother's womb. Instead the fetus receives all of its nutrients and oxygen from the mother via the placenta and the umbilical cord.
The human placenta on average is roughly nine inches long and one inch thick, and weighs approximately one pound. The placenta is connected to the fetus by an umbilical cord that contains two arteries and one vein.
The primary role of the placenta is to provide oxygen and other essential nutrients (sugar, protein and fat molecules) to the fetus and remove carbon dioxide and other waste products from the fetus. In essence, the placenta acts like the kidneys, the lungs and digestive tract for the fetus. It allows the maternal blood and the fetal blood to come very close together, but without ever mixing. Because of this, the maternal blood can pass nutrients and oxygen across to the fetal blood stream, as well as pick up and remove any waste products.
The placenta also plays a vital role with the production of hormones, specifically Human Chorionic Gonadotropin (HCG), which is essential in the sustainability of the pregnancy. When a woman takes a pregnancy test, the test she uses detects the presence of HCG, thereby confirming pregnancy. The placenta is also responsible for producing estrogen and progesterone during pregnancy.
Another interesting fact regarding the placenta is that it has and continues to play an important role in various human cultures, especially in regards to the disposal of the placenta after childbirth. Here in the western world, the placenta is usually incinerated. For a variety of reasons some cultures will bury the placenta, such as burying it to emphasize the relationship between humans and the earth as seen by the Maori of New Zealand, or some, as in Cambodia and Costa Rica, believe that burying the placenta protects and ensures the health of the baby and the mother. Several other cultures have similar rituals. In certain eastern cultures including China and Hong Kong, the placenta is actually eaten, a practice known as placentophagy, as it is thought to be healthy. It is also used in medicines and different health products.
Despite the uses of the placenta after childbirth, the placenta is vital for the welfare of the fetus. Because the fetus relies entirely on the mother to supply all the essential nutrients it needs, one must be careful to avoid substances that may harm the fetus including alcohol, caffeine, herbal substances and drugs, both illegal and prescribed. By eating a healthy diet and taking good care of yourself during pregnancy, you are allowing the placenta to perform at its best, supplying your baby with everything he or she needs.