Congenital malformations are worldwide occurrences striking in every
condition of society. These severe physical abnormalities which are
present at birth and affecting every part of the body happen more often
than usually realized, once in every 33 births. The most common, after
heart defects, are those of the neural tube (the brain and spinal cord)
which happen in as many as one in every 350 births. They have been noted
as curiousities in man and beast throughout recorded history and
received great attention in our time by various fields of study, for
example, their faulty prenatal development by embryologists, familial
patterns by geneticists, causation by environmentalists and variability
by population scientists.
Attention turned much in recent years to the relation of these
malformations to deficiency of a particular dietary ingredient, folic
acid, a subject this book analyzes in depth. The greatest conundrum of
all, which this latest matter like so much else hinges on, is the
amazing fact of the tremendous, almost universal decrease in the
frequency of these anomalies since early in the 20th century. The puzzle
is 'What can this downward trend possibly mean?' and at bottom 'Whether
it is part of a long-term cyclical pattern'. This fascinating biological
phenomenon is explored in the book together with various other topics.