During early pregnancy, a child depends on the mother for hormones, including thyroid hormones. There are also modifications to the mother’s immune system throughout pregnancy. These changes can throw a woman’s hormone balance out of whack and trigger or worsen hypothyroidism.
Hypothyroidism and pregnancy can go hand in hand. 2-3% of women have high TSH levels, which we explain below, before conception — which is a major sign that thyroid problems can occur. 18% of pregnant mothers test for the presence of thyroid peroxidase antibody (TPOAb) or thyroglobulin antibody (TgAb). These antibodies are signs thyroid dysfunction can be present.
We at PrimeHealth believe hypothyroidism is reversible in a large number of patients, including pregnant moms! In pregnant women, thyroid disorders may even go away after the baby is born without significant treatment.
Let’s take a look at how hypothyroidism and pregnancy interact with one another and what to do about it.
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Pregnancy: A risk factor for hypothyroidism?
Pregnancy is a beautiful part of life. However, pregnancy can cause or exacerbate maternal hypothyroidism.
What is hypothyroidism? In endocrinology, when your thyroid doesn’t produce enough T3 and/or T4, that is called underactive thyroid, or hypothyroidism.
- Primary hypothyroidism — your thyroid isn’t producing enough thyroid hormone. (Both “primary” and “central” are called “overt hypothyroidism” as opposed to “subclinical.”)
- Central hypothyroidism — your pituitary gland or hypothalamus is underactive, causing a chain reaction where your thyroid is not stimulated enough.
- Subclinical hypothyroidism — your pituitary gland is overactive, causing high TSH levels, but your thyroid is still producing normal levels of T4 and T3. Around half of “subclinical hypothyroid” cases progress into “overt hypothyroidism.”
Thyroid disease in pregnancy occurs in thousands of women every year. In fact, women are eight times more likely to develop a thyroid condition than men.
Pregnancy can trigger all sorts of hormone imbalances as the mother’s body is growing a life inside her. With the baby deriving thyroid hormones from its mother during the first trimester, a pregnant woman can sometimes find herself with maternal hypothyroidism, whether or not she dealt with thyroid issues before pregnancy.
After the first trimester, the baby’s own thyroid should function within the womb.
If any of the following risk factors for hypothyroidism apply to you, let your doctor know right away:
- Over 30 years old
- Iodine deficiency
- Past infertility
- Past preterm delivery
- Family history of thyroid disease, autoimmune disorder
- Prior radiation exposure to neck
- Thyroid cancer
- Previous thyroid surgery
- Current treatment of hypothyroidism with levothyroxine, unless the dosage is adjusted close to conception
90% of hypothyroidism cases stem from Hashimoto’s disease, an autoimmune disorder that is actually reversible in some cases.
Also called Hashimoto’s thyroiditis, this autoimmune thyroid disease causes your own immune system to form antibodies to attack your thyroid.
Hashimoto’s disease can be triggered by:
- Leaky gut syndrome
- Food sensitivities
- Tick-borne infections or other chronic infections
- Nutrient deficiencies
- Toxin exposure
- Hormone imbalances
If your hypothyroidism is the result of Hashimoto’s, even during pregnancy, we believe treating the underlying causes of hypothyroidism may normalize your thyroid function.
Reversing hypothyroidism is controversial to some — but our patients prove it’s possible.
Spotting Symptoms of Hypothyroidism
Both hypothyroidism and pregnancy can cause chronic fatigue. However, hypothyroidism leads to several other symptoms which make it unique.
Here are the major symptoms of hypothyroidism:
- Weight gain (hard to notice during pregnancy)
- Slow heart rate
- Hoarseness, snoring
- Joint pain
- Muscle aching, tenderness, stiffness, weakness
- High cholesterol
- Cold hands and feet
- Brittle nails
- Thinning hair, eyebrows
- Dry skin
- Impaired memory, trouble concentrating
- Enlarged thyroid (called a goiter)
What happens if hypothyroidism goes untreated during pregnancy?
If thyroid function is not returned to normal levels, patients may develop heart disease, nerve damage, myxedema coma, pregnancy loss (miscarriage), and — in very rare cases — death.
If you exhibit more than four or five of these symptoms, consult your healthcare provider or OB/GYN right away.
If untreated during pregnancy in the mother, hypothyroidism may cause the baby to experience delayed psychomotor skills, stunted hippocampal development, memory issues, and more (discussed in detail below).
Screening for Hypothyroidism During Pregnancy
There are a few tests that your PCP or endocrinologist may run if you are at risk for hypothyroidism.
We encourage all pregnant women to be screened for underactive thyroid because they are at such high risk. Around the ninth week of pregnancy is an ideal time for testing thyroid hormone levels, and it’s generally recommended that at-risk mothers are tested every four weeks during the first half of pregnancy.
One of the most important diagnostic distinctions is whether you developed hypothyroidism during pregnancy or beforehand.
Normal blood tests for hypothyroidism include thyroid-stimulating hormone levels (TSH) and free T4 levels. The American Thyroid Association recommends treatment if serum TSH levels are above 4.0 mIU/L (milli-international units per liter).
However, at PrimeHealth, we believe a more robust set of thyroid function tests helps paint a fuller picture of your thyroid function:
- TSH levels
- Free T4
- Free T3
- Total T4 levels
- Total T3
- Reverse T3
- Anti-thyroglobulin and anti-TPO antibodies (Hashimoto’s thyroid antibodies)
- Thyroid-binding globulin (TBG levels)
Also, we occasionally test for hyperthyroidism (hyper, not hypo), AKA overactive thyroid, as a few symptoms can overlap. Overtreatment of hyperthyroidism can lead to an underactive thyroid.
Ultimately, we encourage every individual to seek out an individualized diagnosis plan, especially when pregnant. Blood tests should not interfere with your pregnancy, but they may cause discomfort.
Miscarriage and Other Fertility & Pregnancy Complications
Hypothyroidism has been linked to pregnancy complications and a number of fertility issues.
Before pregnancy, hypothyroid women may experience heavier than normal menstrual periods. These menstrual changes and serum levels of thyroid-related antibodies and hormones might affect a woman’s fertility.
The good news is that resolving hypothyroidism may lead to successful conception in over ¾ of infertility cases related to an underactive thyroid.
During pregnancy, hypothyroidism can pose a risk to mother and child. Underactive thyroid can lead to adverse outcomes:
- Preterm birth
- Low birth weight
After pregnancy, thyroid problems may still occur. About 8% of women develop a postpartum thyroid disorder within the first year after pregnancy.
Women who are pregnant or breastfeeding should increase their iodine consumption, to prevent iodine deficiency, which can lead to hypothyroidism during or after pregnancy.
For the newborn child, complications of maternal hypothyroidism can last far into childhood. Most common of these include:
- Poor hippocampal development
- Memory problems
- Learning disabilities
- Issues with visuospatial processing (the ability to interpret what the eyes see)
- Problems with motor skills
- Cyclic vomiting syndrome
- Attention problems, potentially similar to those seen in ADHD
Should you treat hypothyroidism during pregnancy?
In general, it’s important to consider the risks of overtreatment and undertreatment when it comes to maternal hypothyroidism.
There are significant risks of miscarriage when TSH levels rise too high. Some sources encourage using a “gestation-specific range” for determining what TSH level is appropriate. This is because TSH will usually fluctuate up during the first trimester, on average to 4.0 MoM for single pregnancies and 3.5 MoM for twin pregnancies.
However, high-quality research in large cohorts of mothers shows that TSH levels over 2.5 MoM in the first trimester are associated with significantly increased rates of miscarriage. This is true even when thyroid dysfunction isn’t obviously present. Interestingly, there isn’t a clear association with high levels of T4 hormones.
Taking these factors into consideration, it is vital for pregnant mothers to maintain a TSH of 0.5-2.5 MoM for the best chance at a healthy pregnancy and birth.
What are the best ways to treat maternal hypothyroidism?
1. Increasing Dosage of Thyroid Medications
Talk to your doctor about adjusting your levothyroxine or other hypothyroid medication dosage, if you take thyroid medication.
Many pregnant women already undergoing thyroid hormone replacement require an increased dose (on average, around 30% more) to maintain healthy TSH levels. It’s a good idea to test every 4 weeks during the first trimester, and at the beginning of the second and third trimesters, to ensure optimal dosage.
We sometimes recommend dessicated thyroid hormones or synthetic, individualized compounded synthetic medication to return maternal thyroid function to normal, rather than levothyroxine.
2. Dietary Adjustments
In normal hypothyroid patients, our first line approach is to start an autoimmune Paleo diet (also known as AIP diet). Unfortunately, this isn’t a great idea for pregnant moms — it’s difficult on AIP to get enough calories and nutrition to grow your new human.
For pregnancy, we recommend getting the obvious culprits out of your diet, like alcohol, excess sugar, gluten, dairy, soy, artificial sweeteners, and processed foods. Focus on nutrient-dense, whole and organic foods with significant calorie counts.
Iodine deficiency is a common source of hypothyroidism. It’s very important to eat iodine-rich foods, such as seaweed, eggs, dairy, and kelp. Optimal iodine intake will improve your chances for the best pregnancy outcome.
3. Prenatal Vitamins
It’s really important to take a prenatal vitamin to keep baby healthy throughout pregnancy (and even before conception!). Although many supplements aren’t known to be safe during pregnancy, including several nutrients that we generally recommend to hypothyroid patients, a prenatal vitamin is a must.
Look for a formulation that includes:
- Vitamin D3
- B vitamins, especially Methyl-Folate (aka 5MTHF)
- Vitamin K2
After the Baby Arrives
Talk to your doctor about adjusting your thyroid medication dosage based on postnatal TSH levels.
Next, continue a higher consumption of dietary iodine until you’ve stopped breastfeeding. Your thyroid function should normalize after breastfeeding stops.
If you developed hypothyroidism in pregnancy, your offspring are more likely to develop thyroid dysfunction later in life. Prepare them for the possibility when the time comes, and keep their iodine consumption at a normal level.
Newborn babies are actually susceptible to underactive thyroid. Fortunately, all 50 states in the United States require universal screenings for hypothyroidism at birth. If newborns are left untreated, congenital hypothyroidism can lead to slow brain development.
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- Hypothyroidism occurs when your thyroid gland or related organs are underactive.
- Unfortunately, early pregnancy can throw thyroid hormone levels out of balance and lead to hypothyroidism.
- If you are over 30, have an iodine deficiency, have a family history of autoimmunity, or already struggle with hypothyroidism, you are more likely to battle hypothyroidism issues while pregnant (specifically, high TSH levels).
- Some symptoms of thyroid dysfunction overlap with pregnancy, but your doctor and/or OB/GYN will use blood tests to determine if your thyroid is underactive.
- The best and safest ways to treat hypothyroidism in pregnancy are:
- Increasing thyroid medication dosage (levothyroxine, dessicated thyroid medications, or compounded synthetics)
- Adjusting your diet to remove major offenders like processed foods and artificial sweeteners, while increasing your intake of nutrient-dense whole foods (particularly those high in iodine)
- Taking a high-quality prenatal vitamin with nutrients your baby’s growing body needs
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