Up to 23% of new mothers experience thyroid dysfunction postpartum — nearly six times the 3–4% rate in the general population — yet thyroid health is rarely part of routine prenatal or postpartum care conversations.
Your thyroid, a butterfly-shaped gland at the front of your neck, produces hormones that regulate your metabolism and help coordinate other hormonal systems in the body. During pregnancy, it increases hormone production by ~50% to support both you and your baby. For the first half of pregnancy, your baby relies entirely on your thyroid hormones; the fetal thyroid gland doesn't mature enough to produce its own until around weeks 16–20. Shifts in thyroid hormones during early pregnancy may even contribute to morning sickness, which typically resolves by the late First or early Second Trimester.
Below, we walk through the most common thyroid concerns during pregnancy and the postpartum period, the nutrients that support healthy thyroid function, and how to advocate for your thyroid health — including through comprehensive testing.
Key Takeaways
- Up to 23% of new mothers experience thyroid dysfunction postpartum, compared to 3–4% of the general population — making postpartum thyroiditis one of the most common yet least-discussed complications of the postpartum period.
- The thyroid increases hormone production by more than 50% during pregnancy, and a baby depends entirely on maternal thyroid hormones until the fetal thyroid matures around weeks 16–20 — which is why healthy maternal thyroid function is closely tied to fetal brain development and pregnancy outcomes.
- The risk of postpartum thyroiditis rises 40–60% when thyroid dysfunction is identified in the first half of pregnancy — and because symptoms like fatigue, hair loss, and mood changes mirror normal postpartum experiences, dysfunction frequently goes unrecognized without testing.
- Iodine and Selenium are the two key nutrients for healthy thyroid function — Selenium also neutralizes the hydrogen peroxide released when the thyroid processes Iodine, which is why adequate intake of both nutrients together supports thyroid health.
- A full thyroid panel — including TPO and thyroglobulin (TGAb) antibodies — before, during, and after pregnancy is the only reliable way to assess thyroid function — ask your doctor or midwife to test, or use an at-home panel if provider testing isn't accessible.
Underactive Thyroid During Pregnancy
Due to the increased demands on the thyroid during pregnancy, the most common thyroid complication that results is hypothyroidism, or an underactive thyroid. This can cause complications for both mother and baby.
Hypothyroidism during pregnancy has been associated with miscarriage, low birth weight, anemia, preeclampsia, gestational hypertension, postpartum hemorrhage, congenital circulation defects, fetal distress, preterm delivery, and an increased risk of cesarean section.
It can also impact fetal development, as the thyroid plays a critical role in your baby's brain development. Some research suggests that maternal hypothyroidism can result in a variety of neurodevelopmental problems such as cognitive delays, delayed verbal development, impaired motor skills, autism, and attention-deficit hyperactivity disorder (ADHD).
Postpartum Thyroiditis
Thyroid dysfunction in postpartum is often referred to as postpartum thyroiditis. Even if your thyroid function was normal throughout pregnancy, problems can still arise postpartum as all of your hormones go through a significant adjustment. That said, the risk of postpartum thyroiditis is higher if problems did exist in pregnancy. In fact, the risk of developing postpartum thyroiditis increases by 40 to 60 percent if dysfunction was identified in the first half of pregnancy.
Postpartum thyroiditis can be hard to identify without testing as symptoms mimic many common complaints during this time - extreme fatigue, depression, hair loss, difficulty losing weight, and trouble producing sufficient breast milk. But it's important to know that dysfunction is quite common (as high as 23% of all new mothers experience thyroid dysfunction postpartum, a significant increase from 3-4% in the general population).
How to Support Your Thyroid During and After Pregnancy
Supporting your thyroid during pregnancy and the postpartum period means providing it with the nutrients it needs to function properly. Two key nutrients include Iodine and Selenium; however, many pregnant women may find it challenging to tolerate foods high in iodine, such as seaweed and fish.
It’s also worth noting that Selenium can have a protective effect against excess Iodine. When Iodine from foods and supplements is processed by the thyroid gland, hydrogen peroxide, a free radical, is released. If too much Iodine is consumed, the excess hydrogen peroxide that is released can be detrimental. However, if the body has adequate levels of Selenium, the Selenium can neutralize the hydrogen peroxide. Therefore, pairing supportive doses of these two nutrients as we do in our Prenatal Multi can help support thyroid health.
Finally, it’s worth noting that proper nutrition supports thyroid function, but does not necessarily prevent dysfunction, so testing and monitoring for symptoms is always recommended.
How to Check Thyroid Function
Before running out to buy a new supplement, you should have your thyroid function tested by your healthcare provider.
Thyroid Testing
The only sure way to know if your thyroid is functioning appropriately is to get tested with a full thyroid hormone panel. A full panel gives you a comprehensive picture of how your thyroid is functioning and shows whether you have thyroid antibodies: thyroid peroxidase antibody (TPO) and thyroglobulin antibody (TGAb). The presence of thyroid antibodies is strongly linked to the development of thyroid issues postpartum.
As thyroid hormone levels can shift dramatically during conception, pregnancy, and the postpartum period, it is recommended to test before, during, and after pregnancy. Unfortunately, this is not typical in many medical practices. We encourage you to ask your doctor or midwife to check your hormone levels. If testing through your provider is not accessible, there are at-home tests available for you to test yourself.
Look for Symptoms
While many women with hypothyroidism have no obvious symptoms, or at least none that can be easily distinguished from other common pregnancy and postpartum symptoms, it’s helpful to know what they are so that you can be aware and bring up any concerns with your provider.
Signs of an underactive thyroid include feeling extremely cold or hot, becoming easily fatigued, a lack of change in appetite, anxiety, irritability, depression, tremor, rapid heart rate or palpitations, dry skin, and difficulty concentrating.
If you already have known thyroid dysfunction
If you already have a known thyroid condition, it's very important to work with your provider to actively monitor your current treatment, as it will likely need to be adjusted throughout pregnancy and the postpartum period. In addition, because too much iodine can be as detrimental as too little, we recommend monitoring your intake of other high-iodine foods (seaweed, seafood, spirulina, dairy, etc.) and discussing supplementation with both Iodine and Selenium with your provider.
Thyroid Health During Pregnancy Frequently Asked Questions
How common is thyroid dysfunction after pregnancy?
Postpartum thyroiditis affects roughly 5–10% of new mothers, with reported rates ranging as high as 22% in some populations. That's a meaningful increase over the general population, which is why the first postpartum year is an important window for monitoring thyroid function.
Why does pregnancy put extra demand on the thyroid?
The thyroid increases hormone production by more than 50% during pregnancy. Your baby depends entirely on your thyroid hormones until the fetal thyroid gland matures around weeks 16–20, which makes healthy maternal thyroid function closely tied to fetal development throughout the first half of pregnancy.
What are the signs of an underactive thyroid postpartum?
Common signs include extreme fatigue, hair loss, difficulty losing weight, low mood, feeling unusually cold, dry skin, and trouble producing sufficient breast milk. Because these overlap with normal postpartum experiences, thyroid dysfunction frequently goes unrecognized without testing — symptoms alone aren't a reliable indicator.
How do I get my thyroid checked?
Ask your doctor or midwife for a full thyroid panel — not just TSH — including thyroid peroxidase (TPO) and thyroglobulin (TGAb) antibodies. Antibody presence is strongly linked to developing thyroid issues postpartum. Testing before, during, and after pregnancy gives the most complete picture; at-home panels are an option if provider testing isn't accessible.
Which nutrients support healthy thyroid function?
Iodine and Selenium are the two key nutrients for thyroid function. Selenium also neutralizes the hydrogen peroxide released when the thyroid processes Iodine, which is why adequate intake of both together supports thyroid health. Talk with your provider about your intake — especially if you have a known thyroid condition, since too much Iodine can be as detrimental as too little.
The bottom line: Be your own advocate
This information is intended to empower you to advocate for your own health and your baby’s health throughout preconception, pregnancy and postpartum. A properly functioning thyroid is critical for your own health and fetal development during pregnancy, and for sufficient energy, mental health, supporting a healthy weight, and remaining fertile for any future pregnancies.
Don’t hesitate to get your thyroid tested before, during, and after pregnancy and support it throughout this entire time period with a high quality prenatal vitamin.
