Vol 43 # 2 June 2011 - Kma.org.kw

June 2011
KUWAIT MEDICAL JOURNAL 89
Review Article
The Knowledge of Teratogenicity in the
Prevention of Congenital Anomalies
Adebisi Sunday Samuel
Department of Human Anatomy, Faculty of Medicine, Ahmadu Bello University, Zaria, Nigeria
Kuwait Medical Journal 2011; 43 (2): 89-98
ABSTRACT
A considerable number of pregnant women need to take
ongoing medication for existing health problems such as
acute respiratory infection or pregnancy complications like
eclampsia. It can be dangerous for such women to avoid
prescription drugs, should they have a medical condition
or become ill; without treatment, the health and welfare of
both the mother and her unborn baby could be at increased
risk. Unfortunately, research has shown that women who
consumed potentially teratogenic drugs – prescribed or not
- during pregnancy had very little information about these
drugs and even less information about their effect during
pregnancy. For this reason, adequate knowledge of this
phenomenon is required both by the pregnant women, to
heed necessary precautions and health workers, to give the
needed advice - prior to and during gestation - with the
onerous task to prevent or reduce the incidence of birth of
monsters. Wide consultation was made in the archives and
contemporary literature to obtain and compile detailed
information on the subject and make them available to
interested readers, in particular the pregnant women, health
workers and researchers in this field. This paper presents
some of the earlier and recent works and publications on the
subject, to update knowledge and information. Although
presently knowledge is inadequate to combat the incessant
menace of birth with defects, the available information, if well
publicized and utilized, will help to guarantee the good health
of the mother and normal development of the conceptus and
hence, lessen the incidence of malformed babies.
KEY WORDS: conceptus, health workers, malformation, pregnancy, teratogens
INTRODUCTION
Teratology from the Greek word teras, meaning
“marvel” or “monster” is the science dealing with
the causes, mechanisms, and manifestations of
developmental deviations of either structural or
functional nature otherwise known as congenital
anomalies or malformations. These structural or
functional abnormalities are present at birth although
they may not be diagnosed until later in life. They
may be visible on the surface of the body or internal
to the viscera. Congenital malformations account for
approximately 20% of deaths in the perinatal period [1-3] .
Hence, this necessitates interest in the knowledge about
the effect of maternal environmental factors on the
conceptus during development, as one or combination
of these factors may act to derail the normal course,
leading to aberrations. Such factors responsible for
this deviation are known as teratogens. A teratogen
therefore, is a drug, chemical, virus, infectious agent,
physical condition, excess or deficiency that, on fetal
exposure, can alter fetal morphology or subsequent
function in postnatal life. However, teratogenicity
depends upon the ability of the agent to cross the
placenta; for instance, certain medications such as
heparin cannot [4-6] .
In general, drugs, food additives, and pesticides are
tested to determine their teratogenicity to minimize
exposure of pregnant women to teratogenic agents.
To prove that a specific agent is teratogenic means to
prove that the frequency of congenital malformations
in women exposed to the agent is prospectively
greater than the background frequency in the general
population. These data are often times not available for
humans and thus cannot be determined in an unbiased
fashion. Therefore, testing is often done in animal
models and often times the drug is administered at
higher than the usual therapeutic doses. However,
there are clearly species differences between teratogenic
effects, limiting this testing in animals [7-9] .
However, some exposures when tested could be
categorized as potent (proven) teratogens (Table 1) [10-
26]
; or probable (possible) teratogens (Table 2) [27-29] ,
based on the following criteria:
• A recognizable pattern of anomalies
Address correspondence to:
Adebisi Sunday Samuel, PhD, Department of Human Anatomy, Faculty of Medicine, Ahmadu Bello University, Zaria, Nigeria.
Tel: +234 805 70 44 301, E-Mail: ssadebisi@abu.edu.ng; sam_adebisi@yahoo.com