Thyroid hormone is secreted from the thyroid gland present in the neck. Thyroid hormone is responsible for the metabolism of carbohydrates and fats in our body , growth of muscles, maintaining good cardiac health, growth and development of children, maintaining body weight, regulating menstruation, and is important for overall active well being in or bodies.

There are fundamentally 2 types of Thyroid hormone deficiencies in our body. Hyperthyroidism and hypothyroidism. Here will be discussing the commoner culprit i.e., hypothyroidism in pregnant females.

Hypothyroidism refers to a condition where the body produces decreased amounts of thyroid hormone as a result of which, patients experience the following symptoms:

• overall: lack of energy, weight gain

• skin and hair: hair loss, dry skin, thick skin, swelling of limbs

• Reproductive health: irregular menstrual cycles, infertility

• Gut: indigestion, constipation, lack of appetite.

• Mental: depressed mental status, worsens existing depressive patients

• heart: slower heart beats and decreased cardiac function leading to increased fatiguability.

• Muscles: stiff and painful muscle , leading to decreased muscular function and muscle growth.

  In Children:

• Decreased mental growth leading to mental retardation leading to decreased scholastic performance

• decreased skeletal growth of the child leading to weak bones and dwarfism in children.

• lethargy

• Impaired reproductive growth

• Decreased and poor reproductive health during puberty and adolescence leading to infertility.

  In severe cases:

• It can lead to extremely harmful conditions like collection of fluid in lungs, around the heart, patient might go into comatose state called "Myxedema Coma"

• decreased bowel movement can lead to impaction of stools in the gut called myxedema megacolon or gaseous distention of the abdomen called myxedema ileus

• extreme fall in cardiac activity leading to decreased cardiac activity and heart failure.

Now what's the big deal with hypothyroidism and pregnancy?

Well, our body requirements of thyroid hormone depend on out hypothyroid status, body weight , the drugs we are on and multiple other factors. Pregnancy is a dynamic condition where the weight and thyroid demand keeps fluctuating with the growth of the fetus.

So, what are some facts that you need to keep in mind in pregnancy?

• During pregnancy, the requirement of thyroxine is increased by 20 to 40%.

• The thyroid doses are adjusted based on TSH levels and the normal range of this TSH levels fluctuate during all 3 trimesters of pregnancy

• Iron supplements taken in the form of Ferrous sulphate, some drugs taken for acidity a.k.a. heart burn impair the normal absorption of thyroid medication.

• Requirement of thyroid hormone comes down in most patients after pregnancy and should be monitored closely for symptoms and TSH levels.

What will happen if the Thyroid doses are not optimized in pregnancy?

Poor control or failure to meet the increased demand of thyroxine hormone during pregnancy leads to the following complications:

• Impairment of mental development in infants leading to decreased intellectual quotient(I.Q.), poor learning skills, autism.

• Higher incidence of miscarriage

• Preterm delivery i.e. delivery before the full development of the fetus leading to poorly developed organ systems in the baby and metabolic complications like diabetes and hypertension in later life.

So, when and how often should I get my TSH levels done when I'm pregnant?

It is important to get your thyroid stimulating hormone (TSH) levels done as soon as you find out that you are pregnant. Once you get TSH levels done, your dose will be increased or adjusted accordingly.

Once you have been started on your adjusted therapy, you need 4 weekly to 6 weekly follow ups with your doctor to further fine tune your doses. As and when your weight increases, your doses will also increase.

First trimester is of utmost importance as the process of developing the organs of your baby for the first time occurs in the first trimester. As and when you enter the second an third trimester, one or two visit would be sufficient, or as advised by your physician. The goal here is basically to fine tune your TSH levels to maintain on the lower range than your non-pregnant levels via therapy.

I'm hypothyroid and planning for pregnancy, what should I do?

If are hypothyroid, it is excellent that you are willing to get your levels done before planning pregnancy.

Optimizing your doses to maintain the lower end of TSH levels is important because:

• Uncontrolled hypothyroidism leads to infertility and decreases the chances of you getting pregnant

• Even if you do get pregnant with poorly controlled hypothyroidism, there are chances that you might end up in a miscarriage with or without you knowing about your pregnancy

• You will be easily fatigues and will have overall poor health in your pregnancy

• Your fetus might develop abnormalities as mentioned above like mental retardation, growth abnormalities etc.

• If you have cardiac condition, it might get worse with hypothyroidism.

I don't have Hypothyroidism and I am planning for pregnancy, should I still be worried?

Screening for thyroid illnesses is generally recommended by many in all pregnant females especially if they have had a family history of thyroid illness.

Many females out there do not necessarily manifest their Hypothyroidism either via symptoms or in lab tests. However, once they get pregnant, this latent disease might end up finally manifesting as pregnancy leads to increasing the thyroid demands and protein alterations (like Thyroid binding protein TBP) in the blood. Since now you are producing a whole new aby inside of you, you will finally manifest with symptoms or on lab tests once you get pregnant if you were on the verge of developing thyroid disease, also known as sub-clinical hypothyroidism.

What if my thyroid stimulating hormone (TSH) levels are not as high but just above the reference range?

This situation is called Sub Clinical Hypothyroidism. Here, the patient doesn't have symptoms but shows only mild lab abnormalities. In this case, your doctor will go ahead with Anti TPO antibodies and decide further as to whether or not to start with therapy.

Lastly, how bad is it to have hypothyroidism during pregnancy?

Well, the good news is that thyroid is a reversible condition . Just taking oral medicines is all you need to do. The outcomes with sticking to therapy are as good as any other normal pregnancy. So, all you need to do is follow up regularly and take those meds.

Is there a difference in how I should be taking my thyroid meds during pregnancy?

Absolutely not. You can continue taking the same way as you would take previously, i.e., empty stomach, preferably in the morning, everyday with a gap of 2 hours between the meal and thyroid hormone pills.

For more info on how to take thyroid drugs and the meds that will affect the absorption of thyroid hormone in your guy, you can read here.

Hope this helps:)

Sources and references:

1. William's textbook of endocrinology, 14th edition.

2. 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum