Which structure minimizes blood flow from the placenta after birth?

After birth, the structure that minimizes blood flow from the placenta is the ductus venosus. This vessel is a significant component of fetal circulation, allowing blood flow from the umbilical vein to the inferior vena cava, bypassing the liver. Once the baby is born and the umbilical cord is clamped and cut, the ductus venosus undergoes closure due to changes in pressure and blood flow. This closure is crucial for redirecting blood circulation away from the placenta, helping to establish the independent circulatory system of the newborn.

The ductus venosus closes to prevent any remaining placental blood from entering the infant’s circulation, which is essential for normal physiological adaptation at birth. This closure leads to the separation of the fetal and maternal blood supply, helping the newborn transition from relying on the placenta for oxygen and nutrients to relying on its own respiratory and metabolic processes.

In contrast, the foramen ovale is another important structure that plays a role in fetal circulation but is not primarily responsible for minimizing placental blood flow after birth. Similarly, the ductus arteriosus, which connects the pulmonary artery to the aorta during fetal life, closes shortly after birth to redirect blood flow to the lungs instead of the placenta.