Many women develop low thyroid symptoms either during pregnancy or right after pregnancy. The majority of these women have Hashimoto’s, an autoimmune disorder in which the immune system attacks and destroys the thyroid gland. The vast majority of hypothyroidism cases are caused by Hashimoto’s. So why do so many women develop hypothyroidism around pregnancy? Pregnancy involves natural shifts in immunity. If your immune system is already out of balance, pregnancy can be the straw that broke the camel’s back.

Here are the factors that can lead to Hashimoto’s low thyroid around pregnancy or childbirth:

  • Changes in immune function during the third trimester
  • Changes in immune function postpartum
  • Significant natural shifts in hormone function
  • Genetic predisposition
  • The worsening of existing health disorders such as blood sugar imbalances, food sensitivities, leaky gut, and other autoimmune diseases, including undiagnosed ones

Why pregnancy can trigger Hashimoto’s low thyroid

About 75 percent of people with autoimmune diseases are women. Researchers believe this is due to their more complex and fluctuating hormonal systems — hormones and immunity affect one another. In fact, hormone imbalances can be a major factor in chronic inflammation and the development of autoimmunity.

Pregnancy simply exacerbates these fluctuations and underlying imbalances.

Immune system fluctuations during and after pregnancy can trigger Hashimoto’s low thyroid

Pregnant women go through significant immune shifts in the third trimester of pregnancy and then immediately after birth. These fluctuations are normal and designed to safeguard the baby.

During the third trimester, the TH-2 arm of the immune system becomes more active. TH-2 is the delayed reaction that produces antibodies to an a foreign invader so the body can recognize and respond to the invader more quickly in the future.

pregnant woman with hypothyroidism


After birth, the immune system becomes TH-1 dominant. TH-1 is the arm that reacts immediately to a foreign invader, as in the example of swelling.

People who are at risk of developing autoimmunity already have an imbalance between TH-1 and TH-2. Pregnancy and childbirth simply push that imbalance over the edge into Hashimoto’s low thyroid.

Pregnancy and the pituitary gland

Although Hashimoto’s causes the majority of hypothyroid cases, sometimes it can be caused by chronic stress. Many women enter pregnancy already highly stressed and of course pregnancy and childbirth bring even more stress.

Chronic stress inhibits function of the pituitary gland, a small gland in the brain that tells the body’s various glands when and how much hormone to secrete.

Chronic stress depresses the pituitary gland with overwhelm. This causes the pituitary to fail at its job of communicating with the body’s endocrine system. As such, thyroid function turns into low thyroid symptoms. This is actually one cause of postpartum depression in some women.

Stress isn’t just about traffic, work, and kids. Other chronic stressors include:

  • Leaky gut
  • Hypoglycemia or insulin resistance
  • Undiagnosed food sensitivities such as gluten intolerance or celiac disease
  • Hormonal imbalances
  • Undiagnosed brain issues, such as from an old brain injury, brain inflammation caused by poor diet, or PTSD or CPTSD
  • Sensitivity to chemicals or over exposure to chemicals
  • Bad liver detoxification
  • Chronic bacterial, viral, parasitic, or fungal infections

Are you at risk for Hashimoto’s? Think you have low thyroid from your pregnancy? Check your TPO and TGB antibodies

Ideally, you would test your TPO and TGB antibodies prior to pregnancy to screen for Hashimoto’s risk. Many people have undiagnosed autoimmunity that is not progressed enough to cause symptoms. However, pregnancy can be the send you over the edge into Hashimoto’s.

Studies show women with no thyroid symptoms had a 25 percent higher risk of developing hypothyroidism after pregnancy if their blood serum TPO antibodies were positive.

Lowering the risk of autism, allergies, eczema, and more in your child

Managing autoimmunity or risk for autoimmunity with functional medicine is not only good for the mom, but also it can help the health of her child. Children born to women with autoimmunity such as Hashimoto’s are more likely to develop autism spectrum disorder, eczema, asthma, food allergies, and food intolerances.

In fact, many cases of autism are caused by an autoimmune attack against the brain. Children born to women with immune system imbalances are more vulnerable to environmental triggers that can trigger autoimmunity.

Triggers can include food sensitivities, blood sugar imbalances, or toxic chemicals delivered into the bloodstream.

Today’s world poses many burdens on the modern immune system. Ideally, you go into pregnancy having identified and managed these risks. If you already developed Hashimoto’s after your pregnancy, knowing why can help you manage it.

Ask my office for help addressing the root cause of your Hashimoto’s low thyroid.