In this article we will talk about hypothyroidism, that is low thyroid levels and its effects on pregnancy. Then we will also discuss how you should manage your hypothyroidism during pregnancy. Pregnancy is a period that places great physiological stress on both the mother and the fetus. When pregnancy is complicated by endocrine disorders such as hypothyroidism, the chances of adverse outcomes increases for both the baby and the mother.
Pregnancy causes major changes in the levels of hormones made by the thyroid gland. For that reason, thyroid problems sometimes can start or get worse during pregnancy or even after childbirth. The thyroid makes the hormones T3 and T4, which control metabolism which in simple terms is how your body uses and stores energy. When the thyroid gland doesn’t make enough thyroid hormone, it is known as underactive thyroid or hypothyroidism.
The symptoms of Hypothyroidism can be confused with the hormonal changes of a normal pregnancy, such as tiredness and weight gain, so low thyroid levels can be overlooked in pregnancy if left untreated, hypothyroidism in the mother poses a risk for both mother and the baby.
A pregnant woman’s thyroid hormones are vital not only for her but also for the development of her baby. Pregnant women with uncontrolled hypothyroidism can get high blood pressure, anemia, muscle pains, and weakness. There is also an increased risk of miscarriage, premature birth, or even stillbirth.
Let’s first talk about what are some of the common signs and symptoms you can develop if you have hypothyroidism and then we will take a look at why thyroid hormones are so important for both the mother and the baby during pregnancy.
When the thyroid gland produces less thyroid hormone than it should, metabolism slows down and causes a variety of symptoms. At first, the symptoms of hypothyroidism may not be noticed, but over time these symptoms become more obvious and severe. These can include;
- Weight gain
- Irregular periods
- Loss of sex drive
- Hair loss
- Brittle hair and nails
- Dry, itchy skin
- Difficulty in learning and memory
- Infertility etc
Causes Of Hypothyroidism
The most common cause of hypothyroidism is an autoimmune disorder called Hashimoto’s thyroiditis. The body’s immune system mistakenly sends out antibodies to destroy the cells in the thyroid gland. This may cause the thyroid gland to enlarge, known as goiter. Hypothyroidism and goiter can also result from not getting enough iodine in your diet.
Hypothyroidism can also occur after thyroid surgery or radioactive iodine therapy given to treat hyperthyroidism. In many cases, the specific cause of hypothyroidism is not known.
Role Of Thyroid Hormones In Pregnancy
Thyroid hormones are vital for the development of the brain and spinal cord of the growing fetus. In 1888 the Clinical Society of London studied the importance of normal thyroid function on the development of the brain. Since that time, numerous studies with rats, sheep, and humans have proven that thyroid hormones have vital importance for various stages of brain development, including the growth of neurons which are the main cells of our brain, and also for the development of the myelin sheath which is like the covering of neurons and is essential for their function.
Studies have also demonstrated a 60% risk of fetal loss if the hypothyroidism in the mother is not controlled. The fetus usually starts producing thyroid hormones when it is about 12 weeks old but it still needs thyroid hormones before 8 weeks as most of the early brain development occurs by the 12th week. Until then the fetus uses the thyroid hormones produced by the mother and due to this, naturally the load on the thyroid gland of the mother increases as it has to produce more thyroid hormones.
It is estimated that the thyroid gland has to produce approximately 50% more thyroid hormones during pregnancy to support the extra requirement of the fetus.
Risk Factors Of Hypothyroidism
Women are at increased risk of hypothyroidism during or after pregnancy if they are over the age of 30 or have:
- Past infertility or preterm delivery
- A family history of thyroid or autoimmune disease
- Type 1 diabetes or other autoimmune diseases
- Prior radiation treatment of the head or neck
- Past thyroid surgery
- Thyroid antibodies, mainly thyroid peroxidase (TPO) antibodies
- A goiter (enlargement of the thyroid gland)
Treatment Of Hypothyroidism In Pregnancy
The treatment for hypothyroidism is thyroid hormone replacement with a form of T4 hormone called levothyroxine. This drug is the same as the T4 your body makes and is safe for pregnant women.
Before pregnancy, it is important that thyroid hormones are at normal levels. If you are already receiving levothyroxine to treat hypothyroidism, you should have your thyroid hormone levels checked before you try to conceive. If your TSH levels are too high, you may need an increase in your dose of levothyroxine. You should delay pregnancy until your disease is well controlled.
Once a hypothyroid woman becomes pregnant, the levothyroxine dose often must increase. The dose should be increased as much as 30% or more in the first 4 to 6 weeks of pregnancy. After that, it is important to monitor the TSH levels and the goal is to keep them below 2.5.
Now 2-5% of females have subclinical hypothyroidism during the pregnancy. Subclinical hypothyroidism is defined as increased TSH with normal concentrations of T4 and T3. This simply means that the thyroid is struggling to keep the thyroid hormones above normal levels. Since multiple studies have shown that subclinical hypothyroidism is associated with an adverse outcome for the mother and offspring, most guidelines recommend that thyroxine replacement should be done in women with subclinical hypothyroidism.
How Is Hypothyroidism Tested?
The main test used to detect hypothyroidism is measuring blood levels of TSH. An elevated TSH level usually means the thyroid gland is not making enough thyroid hormone, and the pituitary gland has responded by making more TSH try to get the thyroid hormone levels where they should be. Other blood tests include measuring T4 Hormone and thyroid autoantibodies. T4 is a hormone produced directly by the thyroid gland. It is typically low in patients with hypothyroidism. Thyroid autoantibodies are seen in patients with Hashimoto’s thyroiditis.
When you get pregnant, TSH levels among many other tests are included in the basic testing profile that every female has to go through when pregnancy is detected. So, the bottom line is Untreated hypothyroidism during pregnancy is associated with adverse effects for both the mother and the baby.
Hypothyroidism during pregnancy could result in abortion, especially in early pregnancy, recurrent pregnancy losses, anemia, pre-eclampsia, gestational diabetes, postpartum bleeding, and an increased rate of cesarean sections. So it’s very important to manage hypothyroidism properly during pregnancy.