Book of Medical Disorders in Pregnancy - Tintash

Chapter No: 13
VIRAL DISEASES IN PREGNANCY
Viral infections during pregnancy are of
great concern to the obstetrician and the
neonatologist because some viruses are
capable of crossing the placenta and
causing serious damage to the fetus.
Acute infections with small pox,
influenza, measles and varicella virus,
may produce profound systemic toxemia.
This may affect both pulmonary and/or
cardiac function and lead to reduced
arterial 02 saturation, which can result in
fetal injury without actually infecting the
fetus. The gestational age at the time of
fetal infection is a critical factor in
producing malformations. In general, the
earlier the interference with normal
patterns of growth occurs, the more
numerous and more severe are the
resultant defects.
The characteristic abnormality produced
in the embryonic host occurs as a result
of pathologic effects of the virus and is
dependent on the quantity and virulence
of the virus. It is also dependent on the
genetic type and conditioning of the host.
There are a number of routes by which
the virus can pass from the mother to her
fetus. This can be better understood by
considering the anatomical relationships
that exist between the mother and the
conceptus. Infectious agents can ascend
from the perineum or introitus through
the vagina or the cervix and enter into
the uterine cavity. These agents either
cross by pyknocytosis or by penetrating
the uterine wall arid result ill infection
and destruction of the fetal membranes.
Once in the amniotic cavity, these
microorganisms might be ingested or
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inhaled by the embryo or the fetus or
penetrate his skin. A tan’s placental
route is the most likely way by which
microorganisms pass from the mother to
the fetus.
Fig13.1: Shows rubella virus rash on
the body
Rubella infection:
The infection with rubella virus is
generally mild. The patient is often an
adult female.
Clinical features: This includes arthritis,
especially of the distal joints, which are
usually symm-etrical. Other features are
malaise, lym-phadenopathy and the
spotty skin. Rash. Coryza, conjunctivitis.
en-cephalitis and throm-bocytopenia
may also occur. Its in-cub-ation period
ranges between 11 to 14 days. The
women who are infected shed virus from
the cervix during the first week of the
disease. In nearly 50 per cent of the
infected cases there is no rash.
Mode of infection - The fetus can be
infected by direct invasion of the virus.
The infection occurs at the time of
maternal viremia. The virus persists and
multiplies in the fetal tissues. In areas