The Placenta: a Multi-Purpose Temporary Organ

The placenta is a temporary organ that develops during pregnancy. It is the only organ of its kind, performing the functions of multiple other organs simultaneously and is discarded when no longer needed. It provides both oxygen and nutrients to the fetus and removes waste from the baby's bloodstream. This waste includes carbon dioxide, which means the placenta acts as a respiratory system. It also helps build the baby's immune system by providing antibodies against diseases.

The placenta begins to develop about a week after sperm fertilizes an egg, in the fourth week of pregnancy. Even though it develops early, the full function of the placenta does not come into play until the second trimester; a mass of cells, the corpus luteum, provides nutrients and hormones for the first trimester of the pregnancy. The placenta completely takes the place of the corpus luteum by the 12th week of pregnancy.

Since a developing embryo has no organs and cannot perform the functions of a human body for many months, the placenta acts as the organs from the second trimester onward. Along with respiratory functions, it helps the baby develop an immune response to potential diseases and immune threats and acts as the liver, gastrointestinal system, kidneys, and endocrine glands.

Scientists recently discovered that the placenta also has a direct effect on the mother's health. It has two parts: one controls hormones for the mother and one is involved in the baby's growth. The mother's part can produce and control hormones such as human placental lactogen, oxytocin, progesterone, estrogen, and relaxin. These affect everything from the start of lactation to muscle relaxation during pregnancy, labor, and birth.

The placenta can grow in different places in different people and this is generally not cause for concern. It attaches to the uterine wall and can develop in the back or front of the uterus. A placenta that attaches to the back of the uterine wall is called a posterior placenta and is most common. An anterior placenta attaches itself between the front of the stomach and the fetus. The organ can also attach to the top or side of the uterus. A placenta that attaches at the bottom of the uterus is potentially dangerous to mother and baby.

Since the placenta completes its role upon the birth of the baby, it needs to be delivered as well. Usually, this occurs during the third stage of labor, after the baby's birth, and without complication. If the baby is born via C-section, the doctor or surgeon will remove the placenta from the uterus. All pieces of the placenta must be removed to avoid internal bleeding or infection.

Complications with the placenta can have both short-term and long-term effects. For example, scientists now know that a healthy placenta can affect the long-term health of a baby. It is also possible that failures in the placental endocrine system are at the root of many pregnancy complications. Studies suggest slow placental growth may correlate to miscarriages or slow fetal development. There are also more direct complications that can have an immediate effect on the baby.

Placenta previa occurs when the placenta grows at the bottom of the uterus and blocks the cervix. It can cause severe bleeding during pregnancy and birth. The danger of vaginal hemorrhage is significant, so delivery of the baby via C-section, before it has reached full-term, is usually the best option.

Placenta accreta occurs when the placenta attaches too deeply into the uterine wall and cannot be delivered normally. Detaching it via operating is possible but can lead to serious bleeding. Placenta previa can leave mothers ar risk for placenta accreta, as can previous uterine surgeries and geriatric pregnancies. A hysterectomy may be required to stop bleeding and remove the placenta and uterus.

The overall health of the mother has a direct effect on placental health. Since nutrients are transported to the baby's bloodstream through the mother, illness, trauma, and an unhealthy lifestyle can all affect the placenta. Exercise is shown to have a direct effect on placenta and pregnancy health. Alcohol, drug use, and smoking can also harm proper nutrient transfer to a developing baby.