Book of Medical Disorders in Pregnancy - Tintash

Chapter No 3
THYROID DISEASE IN PREGNANCY
Fig3.1: shows dissected view of space
for thyroid gland in neck
Thyroid dysfunction in pregnancy is not
a very common complication. The problem
of fertility can arise both from
hyper function as well as hypofunction
of the gland. Hyperthyroidism in severe
form is rarely encountered in pregnancy,
since this causes amenorrhea and infertility.
The incidence reported in the literature
varies between 0.02 to 0.04 per cent
(Hawed and Francis, 1962). Mild cases
of hyperthyroidism are difficult to diagnose
due to hemodynamic and metabolic
changes normally produced in pregnancy.
The physiological changes mimic
clinical features of thyrotoxicosis to
some extent.
Effect of pregnancy on disease:
Hyperthyroidism is usually affected by
pregnancy; In fact pregnancy sometimes
has beneficial effect on this condition.
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Thyrotoxicosis even in its severest form
can be controlled by current therapy and
is therefore not an accepted indication
for termination of pregnancy.
Effects of disease on pregnancy -
Severe hyperthyroidism may produce'
abortion or premature labor in some
cases. The incidence of pre eclampsia is
increased in patients with this complication.
In cases of mild
hyperthyroidism there is little if any
effect on the course of pregnancy.
Effect on infant: It is generally accepted
that thyroxine does not cross the
placenta under normal circums-tances.
Recently it has been reported that small
amounts of thyroxine may some-time
cross the placenta.
This does not appear to harm the fetus in
utero. Hyperthyroidism in the infant can
however result from secon-dary overactivity
of the fetal gland wh-en excessive
secretion of maternal TSH is
present. This is however not perma-nent.
The clinical changes usually disap-pear
in two to three months after birth.
Clinical features:
The changes in cardiovascular system
include tachycardia, ectopic beats, full
bounding pulse, high pulse pressure,
warm skin, sweating and occasional
fibrillation of the heart. Cen-tral nervous
system changes are mani-fested by,
emotional instability of the patient,
which is often quite marked and should
not be missed. There are also fine
tremors of the hands. The eyes may