The source I was citing is "Risk in Mother-Infant Separation Postbirth" by
Gene Cranston Anderson in "Image: Journal of Nursing Scholarship", Vol 21,
Number 4, Winter 1989, p196-199.

"...each time the strain phase of a cry is released, poorly oxygenated blood
flows through the foramen ovale and back into the systemic circulation rather
than into the lungs.  Thus some degree of hypoxemia must develop.  Moreover
this blood flow occurs in a large bolus.  Thus large fluctuations in blood
flow occur.  Each bolus is shunted under high pressure through the foramen
olvae (Lind et al 1964)............From a lifespan perspective, a patent
foramen ovale was found in apparently healthy adults (18 to 35 years) with
shunting occuring at rest in 5 percent and on release of the Valsalve
maneuver in an additional 13 percent.   Patent foramen ovale was found also
in 40% of 60 adults under 55 years of age with ischemic stroke and a normal
cardiac examination.  These investigators concluded that paradoxical embolism
through a patent foramen ovale may be responsible for stroke more often than
is usually suspected."

So, friends, crying may be responsible for more than just sore ears and
"exercise" of the baby's lungs!

Queen of the obscure facts that really need more publication!
Martha Brower RD LD IBCLC and former children's librarian, storyteller and
sales rep.