How does the fetus breath inside the mothers womb ?
We breathe to take in oxygen and to let out carbon dioxide. In a fetus, all of that is done with the blood that flows in through the umbilical cord from mom/placenta. In a fetus, the lungs are all smushed together, and filled with fluid, without any air in them. There are extra holes in the heart of a fetus to let the blood bypass the lungs (only a small amount of blood flows to the lungs in a fetus – just enough blood so that the lungs can grow). When a baby takes its first breath, the lungs fill with air. That, combined with clamping the blood flow from the umbilical cord (cutting the cord), causes changes in the body that should make the extra holes in the heart close up by themselves. If they don’t close, you get a heart murmur. It’s pretty dang cool, I think.
