and now we know ...

The lungs before birth are completely collapsed, and so the
first breaths must inflate the lungs and open up the small
air sacs called alveoli, which are the actual site of oxygen
transfer to the blood. During the last trimester the fetus
starts secreting a fluid called surfactant into the alveoli.
The surfactant lowers the surface tension in the alveoli and
makes it easier to inflate them. Inadequate surfactant
production is one reason why premature infants often have a
much harder time breathing, and they may be given artificial
surfactant or cow surfactant to help them until their own
lungs start producing it. Premature infants also often have
another problem with breathing called apnea -- they
occasionally forget to breathe. For unclear reasons their
respiratory centers are not yet mature enough to control
consistent and continuous breathing.

I have been hanging out with too many babies. There were two at the potluck last night. Two whole babies. babies.