The study of birth defects has assumed an importance even greater now
than in the past because mortality rates attributed to congenital
anomalies have declined far less than those for other causes of death,
such as infectious and nutritional diseases. It is estimated that as
many as 50% of all pregnancies terminate as miscarriages. In the
majority of cases this is the result of faulty development. Major
congenital malformations are found in at least 2% of all liveborn
infants, and 22% of all stillbirths and infant deaths are associated
with severe congenital anomalies. Teratological studies of an
experimental nature are neither ethical nor justifiable in humans.
Numerous investigations have been carried out in laboratory animals and
other experimental models in order to improve our understanding of
abnormal intrauterine development. In less than two decades the field of
experimental teratology has advanced phenomenally. As a result of the
wide range of information that is now accumulating, it has become
possible to obtain an insight into the causes, mechanisms, and
prevention of birth defects. However, considerable work will be needed
before these problems can be resolved. The comributions in this volume
include some of the more recent and exciting observations on the
cellular and molecular aspects of developmental defects. It is not only
a documentation of the latest experimental work, but it also indicates
new and important areas for future research.