As the end of pregnancy approaches, your unborn baby is completely ready to be born. All the body systems have matured and are ready for the changes that come with birth. The most amazing changes occur in the heart and lungs, as they make the transition from using the mother's circulation to breathing in air at birth.

When a baby is born, the umbilical cord is cut and clamped near the navel. This ends the baby's dependence on the placenta for oxygen and nutrition. As the baby takes the first breath, air moves into the lung airways. Before birth, the lungs are not used to exchange oxygen and carbon dioxide, and need less blood supply. The fetal circulation sends most of the blood supply away from the lungs through special connections in the heart and the large blood vessels.

When a baby begins to breathe air at birth, the change in pressure in the lungs helps close the fetal connections and redirect the blood flow. Now, blood is pumped to the lungs to help with the exchange of oxygen and carbon dioxide. Some babies have excess amounts of fluid in their lungs. Stimulating the baby to cry by massage and stroking the skin can help bring the fluid up where it can be suctioned from the nose and mouth. Incredibly, this all happens in the first minutes after birth.