How Do Mothers Transfer Their Cells to the Fetus?
Babies are completely reliant on their mothers, and that's never more the case than when they are still in utero. To meet those needs, a woman's body develops an organ called the placenta. The placenta allows the transmission of vital nutrients, among other things, to the child. But before you can understand the process, you must also know background details about the factors involved.
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What is the Placenta?
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The placenta is an organ that develops during pregnancy. It attaches to the wall of the uterus and is responsible for providing nutrients, gas exchange, hormone regulation, and waste disposal. The placenta begins small and grows in size along with the fetus, eventually becoming large and round. It produces hormones such as progesterone, hCG, and estrogen, all of which play a vital role in sustaining the pregnancy. The placenta is attached to the umbilical cord, which also assists in providing nutrients to the fetus.
What Is the Umbilical Cord?
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The umbilical cord consists of two arteries and one vein. These three blood vessels are wound together and form a tether between the placenta and the fetus. The two arteries carry oxygen rich blood to the fetus, while the vein brings oxygen poor blood back to the mother. The umbilical cord, like the placenta, grows in size and length as the baby does. At full term, the cord can reach lengths of up to 60 centimeters long.
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How Do Nutrients Transfer?
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Once nutrients, oxygen, and hormones are carried to the fetus, an exchange occurs. During this exchange, maternal blood supply flows into small bundles of capillaries within the placenta. These capillaries are part of the fetal blood supply, and on them rest villi, hairlike projections that assist in the absorption of nutrients and other materials from the maternal blood stream. The villi make it possible for the fetus to exchange waste products for nutrients, hormones, and antibodies without ever having to mix with the maternal blood supply.
What Will Transfer?
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Not everything will transfer from mother to fetus. The exchange of nutrients and other substances occurs via diffusion over a selectively permeable membrane and also via active transport. In both, certain substances are allowed through, while certain substances are kept out. For example, viruses and bacteria are usually filtered out by the placenta in order to protect the developing fetal immune system. Yet other potentially harmful substances, such as alcohol or drugs, can and do make it past that placental filter and cause problems for the fetus.
Complications
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There are complications that can occur during any pregnancy, and placental complications are among the most severe. One such complication is placental abruption, a condition in which the placenta prematurely separates partially or completely from the uterine wall. This condition is potentially life-threatening for both mother and fetus. It can deprive the baby of oxygen and nutrients, while also causing heavy internal bleeding in the mother. Slightly less severe is placenta previa, a condition in which the placenta fully or partially covers the mother's cervix. While not usually a problem during pregnancy, it can cause severe blood loss in the mother upon delivery. Usually, however, placenta previa is identified and treated before it becomes too severe.
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- Photo Credit birth of a baby image by Steve Lovegrove from Fotolia.com
