How does a baby's respiration and circulation change when born?

At birth, a baby's respiration and circulation undergo significant changes as they transition from fetal to independent life. The first breath opens the lungs, allowing oxygen to enter the bloodstream, which replaces the need for oxygen from the placenta. This shift causes the closure of fetal shunts, such as the ductus arteriOSus and foramen ovale, redirecting blood flow through the lungs for oxygenation rather than bypassing them. Consequently, the baby's heart and lungs begin to function together to support life outside the womb.