Hypothyroidism In Pregnancy - Effects On Baby

The butterfly-shaped thyroid gland is situated in the neck region of the human body which produces two types of thyroid hormones – Thyroxine (T4) and Triiodothyronine (T3). The thyroid hormone has many functions and is responsible for maintaining multiple metabolic activities in the human body within normal limits. In this article, we will understand briefly what is hypothyroidism, how pregnancy affects thyroid function, and how hypothyroidism in pregnancy affects the baby, and how to prevent such effects.

What is Hypothyroidism?

The word “hypo” means low. So, hypothyroidism is a condition where the thyroid gland produces low than normal amount of thyroid hormones required for maintaining normal metabolic activities.

Many causes can lead to hypothyroidism, some includes:

• Deficient consumption of Iodine
• Autoimmune Hypothyroidism: Where antibodies against the thyroid gland are generated by the body itself, leading to its’ damage
• Drug-Induced: Iodine excess, amiodarone, lithium
• Congenital Hypothyroidism: Where there is a developmental issue of the thyroid gland
• Other disorders: Infiltration and damage of the gland as seen in Sarcoidosis, amyloidosis, hemochromatosis, scleroderma

Apart from this, there are many other rare causes of hypothyroidism. Patient having hypothyroidism often complains of symptoms like

• Tiredness
• Dry Skin and Hair Loss
• Excessive feeling of cold
• Poor memory and concentrating ability
• Constipation
• Weight gain, although appetite is reduced
• An increased amount of menstrual bleed in females (menorrhagia)
• Deep and Hoarse Voice

Effect of Pregnancy on Thyroid Function

Pregnancy is a condition that can alter thyroid function, and in case a woman is previously hypothyroid and on medication, they might need to increase the dose sometimes by as much as 45% during pregnancy. This is because in pregnancy there is increased metabolism of thyroid hormone itself, leading to a low level of the hormone in circulation in blood. The level of thyroid hormone in pregnancy can dip due to

• Increased metabolism of the thyroid hormone by the placenta resulting in termination of hormone's function
• Increased excretion of iodine (this is required for thyroid hormone production) in the urine of pregnant women, thus resulting in impaired thyroid hormone production.

Hypothyroidism in Pregnancy – Effects on Baby

A growing fetus in the initial few months depends on the mother for the hormone. The thyroid hormone is essential for the normal growth of the fetus. And if the mother is herself hypothyroid, it might have an irreversible effect on the baby. Some effects on the baby that can occur due to hypothyroidism in  a pregnant mother include:

• Impaired development of the brain leading to
• Low IQ
• Impaired Psychomotor Development
• Impaired learning activities in Children
• Attention Deficit Hyperactive Disorder
• Preterm Birth
• Low Birth Weight
• Respiratory distress at Birth

Prevention of Hypothyroidism Effects on Baby During Pregnancy

As we have noticed that hypothyroidism can affect the baby, leading to devastating life-long consequences. However, this can be prevented. Once a woman gets pregnant, she should get tested for thyroid disorders. And for those who are already hypothyroid, the TSH should be tested every four weeks during the first half of the pregnancy and later at a less frequent interval after 20 weeks of pregnancy. The levothyroxine supplement dose should be adjusted in such a way that the TSH level in the blood stays in the lower half of the normal range for the specific trimester or <2.5 mIU/L.

In case the pregnancy is planned, then achieving a TSH level of <2.5 mIU/L before conceiving is advisable. However, self-adjustment of dose should not be done and should only be done under a physician’s supervision.