In placental mammals, the umbilical cord (also called the navel string, birth cord or funiculus umbilicalis) is a conduit between the developing embryo or fetus and the placenta. During prenatal development, the umbilical cord is physiologically and genetically part of the fetus and (in humans); normally contains two arteries (the umbilical arteries) and one vein (the umbilical vein), buried within Wharton’s jelly.
The umbilical vein supplies the fetus with oxygenated; nutrient-rich blood from the placenta. Conversely, the fetal heart pumps low oxygen-containing blood, nutrient-depleted blood through the umbilical arteries back to the placenta. The umbilical cord develops from and contains remnants of the yolk sac and allantois. It forms by the fifth week of development, replacing the yolk sac as the source of nutrients for the embryo.
The cord is not directly connected to the mother’s circulatory system; but instead joins the placenta, which transfers materials to and from the maternal blood without allowing direct mixing. The length of the umbilical cord is approximately equal to the crown-rump length of the fetus throughout pregnancy.
The baby’s umbilical cord
A baby’s umbilical cord is typically clamped and cut immediately after birth. Over the years, emerging research has suggested there may benefit to delaying umbilical cord clamping in term neonates. However, it was not clear if this intervention would also have benefits on the survival of extremely low gestational age preterm neonates.
In a new study published in JAMA Network Open, neonatologist Dr. Abhay Lodha, MD, and his research team found for the first time that delaying umbilical cord clamping in extremely preterm babies improves their survival. It also lowers the odds of severe neurological injury in the form of intraventricular hemorrhage or bleeding in the brain.
“Delaying cord clamping allows time for the baby’s blood pressure to stabilize. “As premature babies’ brain vessels are quite fragile, a rapid change in blood pressure can rupture their blood vessels; causing a brain hemorrhage.” In this retrospective cohort study; researchers analyzed the outcomes of 4,680 neonates across Canada who were born at 22 to 28 weeks and were admitted to a neonatal intensive care unit (NICU).
Umbilical cord clamping
Therefore the studies suggest deferred umbilical cord clamping (DCC) leads to circulatory stability; which improves blood pressure and reduces the need for transfusions. The researchers also found DCC reduced the risk of infection by allowing the newborn to receive more nutrient- and immune cell-rich blood from the mother. As long as the baby is stable at the time of birth, we recommend delaying umbilical cord; clamping for 30 to 60 seconds.
“This is a simple intervention that could reduce the need for medication to treat hypotension; reduce the risk of infections, and improves the baby’s survival. They hope this new information will have a global impact; especially in developing countries and save many premature neonates.” Going forward, the research team plans to study the long term neurodevelopmental outcomes of preterm neonates who received DCC at birth.