During fetal development, when the interatrial septum is being formed, a small passageway called the " foramen ovale" is left open to allow the blood to bypass the non-functional fetal lungs while the fetus obtains oxygen from the mother's placenta.

在胎儿时期，当房间隔正在形成时，残留下一个被称之为为“卵圆孔”的细小通道，允许血液绕过无功能的胎儿肺，而胎儿是从母亲的胎盘获得氧气。