How the placenta develops
The placenta is a unique organ because of its temporary nature. Partly formed from maternal cells, and partly from fetal cells, this organ nourishes a baby throughout pregnancy, provides it with oxygen and water. The placenta is also the way in which the baby gets rid of waste products like carbon dioxide. The placenta starts to form immediately after a fertilized egg implants itself into the uterus, but it takes over hormone production necessary for the pregnancy after 12 weeks.
A placenta usually attaches on the upper side of the uterus. The average human placenta is 22 centimeters long by the end of a pregnancy, and between two and three centimeters thick. One side will have membranes and blood vessels running along it, and that is where the umbilical cord also attaches to the baby. The placenta is definitely one of the most under-appreciated organs humans produce. Many new mothers never even get to see their placenta, and think it is really gross. A few "alternative folks" make placenta art with their placenta, bury it under a tree, or even eat it.
They are part of a tiny minority who celebrate their placenta and recognize the important part it plays in a pregnancy. The rest of us only remember the "tree of life" when something goes wrong with it. Unfortunately, there are quite a few placental complications that can crop up during a pregnancy. Many of them are potentially fatal. So, what can go wrong with a placenta? Placenta previa Placenta previa is a placental complication in which the placenta grows over the cervix (the opening between the uterus and vagina), or close to in in the lower part of the uterus. In many cases, earlier ultrasounds will show a placenta growing relatively close to the cervix. In most cases, a low-lying placenta that was identified during the second trimester will have "moved up" by the the time a woman reaches her third trimester of pregnancy.
That is because the uterus unfolds downwards in the later stages of pregnancy to accommodate the growing baby. A placenta cannot move from the location at which it implanted, but its position relative to the cervix can and does change. If the placenta still covers the cervix toward the end of the pregnancy, you're dealing with a true case of placenta previa. The placenta is located between the baby and the birth canal, and there is no way the baby can be born vaginally. Even going into labor is dangerous with a placenta previa, since the placenta is the baby's source of oxygen and it would be compromised if the baby started pressing on it, and the placenta started detaching. A planned, early c-section is therefore the best course of action.
A placental abruption is pretty much what it sounds like the placenta detaches from the uterine wall before it is supposed to, either during pregnancy or while labor and delivery are already ongoing. A placental abruption can be partial or complete. With a partial placental abruption, a section of the placenta peels away from the uterine wall, while the larger part of it is still attached. This can harm the baby over time, but the pregnancy can still be sustained in many cases. A complete abruption doesn't offer that luxury; with all of the placenta detached before the baby is born, the baby's only source of oxygen is lost and she is in immediate danger. A sore and tender abdomen and contractions that come rapidly one after the other can indicate a placental abruption. Vaginal bleeding is another possible symptom, but though internal hemorrhage is always a consequence of placental abruption, the blood may remain inside the body. As a result, the uterus may feel really firm and could be suddenly enlarged. If diagnosed on time, an emergency c-section is the appropriate management of placental abruption.
Placenta accreta is the third serious placental complication. Unlike placenta previa and placental abruption, it rarely poses a risk to the fetus. With placenta accreta, the maternal portion of the placenta is embedded in the uterine wall much more deeply than it is supposed to. There are various degrees of placenta accreta, and the most serious version involves the placenta cutting all the way through the uterus' muscular structure. Placenta accreta is often hard to remove. Not easily diagnosed through ultrasound, the first indication that placenta accreta is present is commonly the delay in its expulsion after the baby's birth. Some women with placenta accreta experience vaginal bleeding in the third trimester. Sometimes, a hysterectomy needs to be performed to be able to remove the placenta.