Ace the CVS Pharmacy Exam 2026 - Your Prescription for Success!

Functional closure of the foramen ovale typically occurs within the first few hours after birth. The foramen ovale is an opening between the right and left atria of the heart that allows blood to bypass the lungs during fetal development, as the fetus receives oxygenated blood from the placenta. Upon birth, when the newborn begins to breathe air, the pressure in the left atrium increases due to increased blood flow from the lungs, leading to a functional closure of the foramen ovale. This closure effectively redirects blood flow through the lungs to be oxygenated, establishing normal postnatal circulation.

While anatomical closure may take longer, the critical functional aspect is that it occurs quickly after birth, making the timing crucial for proper circulatory adjustments. Consequently, stating that it transpires within hours aligns most accurately with physiological changes occurring immediately following the transition from fetal to neonatal life.