What happens to blood flow across the Foramen ovale after birth?

After birth, the Foramen ovale, which is a small opening between the right and left atria of the fetal heart, typically closes off as pressure changes occur in the heart. During fetal life, the right atrium has higher pressure due to the presence of placental circulation, allowing blood to flow from the right atrium to the left atrium through the Foramen ovale, bypassing the non-functioning lungs.

At birth, the baby's lungs inflate, leading to a decrease in pressure in the right atrium and an increase in pressure in the left atrium as blood returns from the lungs. This change in pressure dynamics helps to functionally close the Foramen ovale, creating a separation between the two atria. Over time, this closure may become permanent as the interatrial septum fuses.

Understanding this physiological transition is crucial in recognizing the normal changes that occur in the heart's structure and function immediately after birth. This closure is significant in preventing right-to-left shunting that could lead to potential complications if it does not occur properly.