Baby's first breath, how?

When a fetus is in amniotic fluid, it mimics breathing motions without gas exchange happening in the lungs. So the fetus’s lungs are filled with amniotic fluid, no problem I guess. Except if an adult’s lungs are filled with fluid, even a relatively benign fluid, it’s tremendously difficult to clear them to allow normal breathing. That would be a medical emergency, and yet newborns have (relatively) no trouble taking that first breath. Obviously this works out fine in most cases, but I’m failing to see the mechanism that clears the newborn infant’s lungs of fluid to allow for air to flow. I could imagine a few scenarios that all seem unlikely. Don’t shake the baby and all that.

I guess I didn’t phrase that as a question. How is it that a newborn’s lungs empty themselves of liquid to a sufficient degree to allow for them to begin normal respiration?

This is an interesting article about the process http://www.nlm.nih.gov/medlineplus/ency/article/002395.htm

Thanks! I already did a google search, finding that one and a few others. It really only says that it happens, though, which is obvious enough from the evidence. How?

My recollection is that it’s generally squeezed out by vaginal birth.

Found this:

When my twins were born via C-section the doc used a sucker kind of like thisbut bigger to get the fluid out of their mouths and noses.
A few pulls with one of those thing and the kids reacted pretty strongly, coughing and spitting, and I suspect finished the job on their own

Since all placental mammals face this situation, it’s nice to know we’ve had at least 100M years of evolution to work the kinks out of this issue. Otherwise… oops!

This appears to indicate there isn’t much fluid in the lungs to begin with:

http://en.wikipedia.org/wiki/Development_of_human_lung

True, of course. But really, all air-breathing vertebrates have this issue; I was just imagining that the difficulty involved was one of air volume. It’s not hard to imagine that a newborn chick would have little difficulty initially pulling open the lungs against the stresses involved, but an elephant should have it much worse than we do. And my goodness, whales.