One of the main differences between adult and fetal circulation is <em>the direction and where the non-oxygenated and oxygenated blood circulates</em>. In adults arteries carry oxygenated blood away from the heart and veins carry non-oxygenated blood towards the heart; in fetuses, arteries carry non-oxygenated blood away from the heart and veins carry oxygenated blood back to the heart.
Another difference is <em>where does the exchange of gases takes place</em>, in fetuses blood is oxygenated in the placenta, in adults in the lungs.
The circulation between adults and fetuses differs in <em>where does the pressure increases</em>, in adults is on the left side of the heart, in fetuses on the right side.
Finally,<em> another important difference between adults and fetuses is the presence of shunts</em>, in fetuses these shunts allow both sides of the heart to work parallelly letting mix blood from both ventricles. This shunt gets closed after birth, so adults do not have them.
I hope you find this information useful! Good luck!
