The umbilical cord connects mother and child during pregnancy in the womb. The fetus is connected to the mother’s bloodstream via the placenta. It loses its importance after birth.
What is an umbilical cord?
The umbilical cord is a tube of tissue that provides a connection between the mother’s placenta and the baby’s abdomen. Its development is closely related to the development of the placenta. The fertilized egg already consists of several cells and continues to develop in the uterus. The outer shell of the egg fuses with the mucous membrane of the uterus to form the placenta. Thus, it is a union of maternal and embryonic cells. It not only influences the supply of the fetus, but also affects the mother’s organism. Its interior forms cavities filled with blood. From them the blood vessels develop until the fourth week of pregnancy, from which the blood vessels for the umbilical cord are formed. By the end of the fourth week of pregnancy, the embryo has developed to the point where its heart begins to beat. At that moment, the umbilical cord takes up its function, which is to ensure the supply of nutrients and oxygen. It is also responsible for disposing of metabolic waste products such as carbon dioxide.
Anatomy and structure
When the baby is born, the umbilical cord is 50 to 60 centimeters long and 1.5 to two centimeters thick. It is composed of a gelatinous connective tissue that is coiled in a spiral. The cord is composed of collagens, a few fibroblasts, and a high amount of water-binding hyalurons (Wharton’s sulcus). It is flexible to be able to accompany the baby in its movements and not injure it. During pregnancy, the child also begins to reach for the umbilical cord, play with it, bend it and, in some cases, chew on it, so it is exposed to a lot of stress. Its composition protects the internal blood vessels from kinking and thus interrupting the supply.
Function and tasks
Initially, the umbilical cord still consists of four blood vessels, two of which are umbilical arteries and two of which are umbilical veins. The right umbilical vein regresses by the fourth week of pregnancy. The arteries carry blood that is low in oxygen and nutrients but high in carbon dioxide to the placenta, and the veins carry oxygen and nutrients to the baby. The exchange takes place in the placenta without the mother’s and baby’s circulations overlapping through the blood. After birth and the first breath of the child, the umbilical cord loses its task and after cutting it also loses its functionality. It is therefore possible for the child to be supplied simultaneously by both the umbilical cord and its own breathing. If the child breathes regularly, it becomes white and limp. At this point, it can be cut without complications. At two points, a few centimeters from the baby’s abdomen and a few centimeters from the placenta, it is each fitted with an umbilical clamp. It is then cut. The baby has no nerve cells on this part of the umbilical cord, so cutting it does not hurt either. The piece that remains on the baby’s abdomen is cleaned and bandaged. Within a few days, it dries up and eventually falls off. The belly button is then formed at this point on the abdomen.
Diseases and ailments
If only one umbilical artery is detected, it is called singular umbilical artery. This occurs in about one percent of all pregnancies. If it is detected, the risk of chromosomal or organ malformation is increased by 30 to 60 percent. An umbilical cord that is too short can also indicate malformations. For example, the fetus may not be able to move sufficiently as a result of a disorder in the central nervous system. It may also indicate that the muscles are not well enough developed. If the umbilical cord is too long, the risk of cord tangling is higher. If the baby moves too much, the cord can either kink, which is called a false knot, or form an actual knot. For the latter, the incidence is one to two percent of pregnancies. In either case, this is usually not associated with negative consequences for the child, although blood circulation may be briefly disrupted. The tissue that makes up the umbilical cord usually prevents bad consequences.A greater danger is the umbilical cord entanglement. It can wrap around individual parts of the child’s body. Especially if it wraps around the neck, this can be dangerous. This type of entanglement occurs in 20 to 30 percent of children at birth. If the umbilical cord is compressed in such a way that the blood flow is disrupted, the child must be brought into the world as quickly as possible, either by forceps delivery or a cesarean section. A special case is the prolapse of the umbilical cord. Here, the umbilical cord gets caught in the birth canal in front of the baby’s body. Here, too, the birth must take place quickly. In the case of a ruptured umbilical cord (omphalocele), the child’s organs, such as the intestines or liver, protrude from the abdomen. However, they continue to develop outside the abdomen. This can already be seen on ultrasound and can be repaired by surgery immediately after birth.
