A foramen ovale is a hole in the heart. The small hole naturally exists in babies who are still in the womb for fetal circulation. It should close soon after birth. If it doesn’t close, the condition is called patent foramen ovale (PFO).PFOs are common. They occur in roughly one out of every four people. If you have no other heart conditions or complications, treatment for PFO is unnecessary.While a fetus develops in the womb, a small opening exists between the two upper chambers of the heart called the atria. This opening is called the foramen ovale. The purpose of the foramen ovale is to help circulate blood through the heart. A fetus doesn’t use their own lungs to oxygenate their blood. They rely on their mother’s circulation to provide oxygen to their blood from the placenta. The foramen ovale helps blood circulate more quickly in the absence of lung function.When your baby is born and their lungs begin to work, the pressure inside their heart usually causes the foramen ovale to close. Sometimes it may not happen for a year or two. In some people, the closure may never happen at all, resulting in PFO.