The umbilical cord serves as a connection during pregnancy between a developing fetus and the placenta. This structure forms early in gestation, around the fifth week, facilitating the transfer of oxygen and nutrients from the birthing parent to the fetus. It also plays a role in carrying waste products away from the fetus to be processed by the birthing parent’s body. This continuous exchange supports the fetus’s growth and development throughout pregnancy.
External Appearance
The umbilical cord presents an appearance both during pregnancy and at birth. It looks like a thick, flexible rope, often displaying spirals or coils along its length. These coils contribute to the cord’s strength and help prevent the compression of the vessels within it. At full term, an umbilical cord measures about 50 to 60 centimeters (approximately 20 inches) in length, though its size varies, ranging from 30 to 100 centimeters. Its diameter is around 2 centimeters (0.79 inches).
Immediately after birth, the cord appears pearly white to bluish-white and may feel damp and shiny. It connects directly from the fetus’s navel, which will later become the belly button, to the placenta, an organ attached to the uterine wall. The cord’s texture is gelatinous or smooth, reflecting its internal composition.
Internal Composition
The cord’s external appearance relates to its internal makeup. Within the umbilical cord, there are three blood vessels: two umbilical arteries and one umbilical vein. The single umbilical vein transports oxygenated, nutrient-rich blood from the placenta to the fetus. Conversely, the two umbilical arteries carry deoxygenated blood and waste products away from the fetus, back to the placenta for removal.
These vessels are encased and protected by a specialized gelatinous substance known as Wharton’s jelly. This jelly provides cushioning and insulation, protecting the blood vessels from compression or kinking, which is particularly important during fetal movement and birth. Wharton’s jelly is primarily composed of mucopolysaccharides.
Post-Birth Changes
Immediately following birth, the umbilical cord is clamped and then cut, a procedure that is painless for both the baby and the birthing parent as the cord contains no nerves. This leaves a small piece of the cord, known as the umbilical stump, attached to the baby’s abdomen. The stump undergoes a drying and healing process in the days following delivery.
Initially, the stump appears shiny and yellowish or bluish-white and feels damp. As it dries, it shrinks, shrivels, and darkens in color. The color changes from yellowish-green to brown, gray, or black as the tissue dries out.
The umbilical stump falls off naturally within one to three weeks after birth. Once the stump detaches, it leaves behind the baby’s belly button, or navel. A small raw area might be visible initially, and some light bleeding or clear to yellowish fluid can be present as the area heals. Sometimes, a small, pinkish-red lump called an umbilical granuloma may form, which resolves without intervention.