Persistent fetal circulation

Persistent fetal circulation is a condition caused by a failure in the systemic circulation and pulmonary circulation to convert from the antenatal circulation pattern to the "normal" pattern.

In a fetus, there is high pulmonary vascular resistance and low pulmonary blood flow as the fetus does not use the lungs for oxygen transfer. When the baby is born, the lungs are needed for oxygen transfer and need high blood flow which is encouraged by low pulmonary vascular resistance.