Preparing for Pregnancy When You're Hypothyroid

Patient Expert
Medically Reviewed

When you’ve decided to become a mother, nothing is more important than ensuring a healthy pregnancy and healthy baby. If you are being treated for hypothyroidism and are planning to have a baby, there are some important thyroid-related steps to take before you try to conceive. These steps can make all the difference to a healthy and successful pregnancy.

Step 1: Start planning six months in advance

Whenever possible, experts recommend that you start your planning at least six months before you try to conceive. This allows you time to test for and supplement with any missing nutrients, ensure that your thyroid levels are optimal for fertility and pregnancy, and develop a plan with your practitioner to carefully manage your thyroid during early pregnancy. In addition to iodine levels, some other preconception tests you may want to discuss with your practitioner include ferritin, the stored form of iron that is important to hormonal health and fertility; vitamin D; vitamin B-12, and magnesium.

Step 2: Optimize your thyroid levels for fertility and early pregnancy

According to the 2017 "Guidelines of the American Thyroid Association (ATA) for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum," your dosage of thyroid hormone replacement medication should be adjusted so that your thyroid stimulating hormone (TSH) level is below 2.5 mIU/L before you conceive. If your TSH levels are higher, your doctor should raise your thyroid hormone replacement dosage, and recheck your levels until your TSH level is 2.5 or less.

Step 3. Ensure that you are not iodine deficient, and supplement with iodine

Iodine is the key building block for thyroid hormone, and during early pregnancy, your need for iodine increases. If you are hypothyroid and have not had your thyroid surgically removed or disabled due to radioactive iodine (RAI) treatment, consider being tested for iodine deficiency prior to conception. If you are low in iodine, your practitioner can recommend an appropriate level of iodine supplementation. Typically, an iodine/iodide combination formula such as Iodoral or Lugol’s solution are the recommended forms.

If your iodine levels are not deficient, the ATA Guidelines still recommend that you supplement with a multivitamin or prenatal vitamin that includes at least 150 μg of iodine. If you are taking a vitamin prior to conception, be sure to check the label, as many over-the-counter and prescription prenatal vitamins do not include iodine. The ATA recommends that you continue taking a vitamin with iodine throughout your pregnancy and while breastfeeding.

Step 4. Take the right kind of folic acid

Prior to conception and during pregnancy, folic acid is a crucial nutrient to help prevent neural defects in your baby. According to the National Institutes of Health, up to 25 percent of the U.S. population has a methylenetetrahydrofolate reductase mutation, also known as an MTHFR genetic mutation. Among other effects, the MTHFR mutation makes it hard to effectively metabolize folic acid.

MTHFR mutation is more common in people with autoimmune diseases and thyroid conditions. Prior to pregnancy, you can have genetic testing to determine if you have the MTHFR mutation. If you test positive, experts recommend that you take a methylfolate form of folic acid before and during pregnancy. This form of folic acid will help prevent neural tube defects in your baby. If you don’t have the MTHFR testing, many practitioners recommend that you take methylfolate in place of folic acid, given the prevalence of this genetic defect.

Step 5: Confirm your pregnancy as early as possible

In a woman without a thyroid condition, as soon as conception takes place the thyroid gland starts to enlarge and begins to increase production of thyroid hormone by as much as 50 percent. This increased level of thyroid hormone is essential for your developing baby, whose thyroid is not fully formed and able to produce thyroid hormone until the start of the second trimester. Whether you don't have a thyroid or are hypothyroid for other reasons, it is essential to confirm your pregnancy as early as possible, so that you can increase your dose right away. This can help reduce your risk of a thyroid-related miscarriage, or if the pregnancy continues, reduce the risk of developmental or cognitive deficits in your baby. Don’t wait for a missed period. You should start pregnancy testing soon after you try to get pregnant. Some home pregnancy tests are so sensitive that they can confirm pregnancy as early as seven days after conception

Step 6: Have a plan to increase your thyroid medication dosage

During your pre-conception planning with your practitioner, have a plan in place for an agreed-upon dosage increase of your thyroid medication that you will start as soon as you have a positive pregnancy test. In some cases, practitioners will recommend that you increase your dose by as much as 50 percent after confirming your pregnancy.

Step 7: Get retested as soon as your pregnancy is confirmed

As soon as you have confirmed your pregnancy and started on your predetermined dosage increase, you should coordinate with your practitioner to have your thyroid levels checked. That way, you can quickly ensure that your TSH levels are not exceeding the ATA Guidelines’ recommendation to maintain your TSH level between 0.1 and 2.5 mIU/L during your first trimester.

See more helpful articles:

Pregnancy Complications and Your Thyroid

Thyroid Problems After Pregnancy

Breastfeeding and Thyroid Disease