The umbilical cord serves as the connection between a developing fetus and its mother during pregnancy. This flexible, tube-like structure provides a lifeline, facilitating the exchange of substances necessary for fetal growth and development. It is formed early in gestation, around the fifth week of pregnancy, and attaches to the fetus at the abdomen, eventually forming the belly button after birth.
The Umbilical Cord’s Vital Role
During pregnancy, the umbilical cord functions as a conduit, transferring oxygen and nutrients from mother to fetus. It also removes waste products, like carbon dioxide, returning them to the mother for elimination.
The cord contains three main blood vessels: two umbilical arteries and one umbilical vein. The umbilical arteries carry deoxygenated blood and waste from the fetus to the placenta, while the umbilical vein transports oxygenated, nutrient-rich blood from the placenta to the fetus. These vessels are encased within Wharton’s jelly, a gelatinous substance that provides protective cushioning against compression and twisting, ensuring uninterrupted blood flow. The average length of a full-term umbilical cord is about 50 to 60 centimeters (approximately 20 to 24 inches), with a diameter of 1 to 2 centimeters (about 0.4 to 0.8 inches). This structure acts as the fetus’s temporary lungs, heart, and gastrointestinal system.
The Moment of Separation at Birth
After birth, once the newborn can breathe independently, the umbilical cord’s function ends. Healthcare providers then clamp and cut the umbilical cord. This action is painless for both the mother and the baby because the cord contains no nerve endings.
The process involves placing two clamps on the cord a few centimeters from the baby’s belly, then cutting the cord between them, leaving a small stump attached to the newborn’s abdomen. Historically, clamping was often immediate. Current practices favor delayed cord clamping, where the cord is cut between 30 seconds to several minutes after birth, or until pulsations cease. This delay allows for a greater transfer of placental blood to the infant, which can increase the baby’s blood volume and improve iron stores. For premature infants, delaying clamping for at least 60 seconds has been associated with reduced mortality and major disability at two years of age.
After Birth: From Stump to Navel
After the umbilical cord is cut, a small stump remains attached to the baby’s abdomen. This stump undergoes a natural drying process, shriveling and changing color from yellowish-green to brown or black as it heals. Over a period of approximately 5 to 15 days, or sometimes up to three weeks, the stump will naturally detach and fall off on its own, similar to a scab.
Proper care of the umbilical stump involves keeping the area clean and dry. Exposing the stump to air as much as possible aids the drying process, often by folding the top of the baby’s diaper down below the stump. Sponge baths are advised until the stump has fallen off and the area is fully healed, to keep the stump dry and prevent submersion in water. Parents should avoid pulling or picking at the stump, even if it appears to be barely attached, allowing it to fall off naturally.
The navel, or belly button, forms as the skin heals after the stump detaches, essentially becoming a scar. The appearance of the navel, whether an “innie” (an inward depression) or an “outie” (a protrusion), is largely determined by how the skin heals and is generally a cosmetic variation, not indicative of health issues.
Common Umbilical Concerns
While the umbilical stump usually heals without complications, issues can arise. An umbilical granuloma is a common condition that may appear as a small, moist, pink or red lump of tissue at the navel after the stump falls off. This overgrowth of scar tissue does not cause pain and may ooze a small amount of clear or yellowish fluid. While some granulomas resolve on their own, a healthcare provider might recommend salt treatment or silver nitrate application to help it shrink and dry.
Another concern is an umbilical hernia, which presents as a soft swelling or bulge near the navel. This occurs when a portion of the intestine or abdominal lining pushes through a small opening in the abdominal muscles that did not fully close after birth. Umbilical hernias are common in infants, particularly premature babies, and often close on their own by the age of four or five years. Signs of a potential infection in the umbilical stump include persistent redness or hardening of the skin around the stump, swelling, a foul odor, or yellowish pus-like discharge. Fever, poor feeding, or lethargy in the baby, alongside these local signs, warrant immediate medical attention.