Taussig did extensive work on Anoxemia. The most common cause of blue baby syndrome is Tetralogy of fallot.

Taussig, along with Alfred Blalock, a surgeon, and Vivien Thomas, an African American surgical tech, discovered that tetralogy of fallot is caused by a partial blockage of the pulmonary artery alone or combined with a hole between the ventricles of an infants heart.

Because of the blockage oxygenated blood cannot get through the arteries, and can cause an abnormal mixing of oxygenated and deoxygenated blood between the left and right ventricles, and into the aorta.

The pumping of the mixed blood throughout the body causes the baby to appear blue.