What to Know About Hashimoto’s Disease and Pregnancy

Hashimoto’s disease is an autoimmune thyroid disorder. That means your immune system mistakes your thyroid gland for a pathogen—something that can make you sick. It launches an attack and tries to destroy thyroid cells. Damage from that attack makes it hard for the gland to produce enough thyroid hormones.

What Are Thyroid Hormones?

Your thyroid gland makes two hormones: triiodothyronine (T3) and thyroxine (T4). T3 is more active in the body. Other organs, including the liver and kidneys, can use T4 to create T3 when it's needed.

Those hormones control your metabolism. They impact your weight, energy, sex hormones, and more. Low thyroid hormone levels can lead to irregular menstrual cycles, problems getting pregnant, complications during pregnancy, an increased miscarriage risk, and an increased risk of low birth weight.

A Black woman and doctor lay their hands on her pregnant belly.

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Hashimoto’s and Fertility

Hashimoto’s disease can make your periods irregular. That can make it hard for you to get pregnant. Taking the right dose of replacement thyroid hormones should regulate your periods and help you conceive.

It’s safest to wait to get pregnant until your thyroid disease is well controlled. Of course, not all pregnancies are planned. If you have untreated or undertreated Hashimoto’s and find yourself pregnant, contact your doctor right away. You may need an obstetrician who specializes in high-risk pregnancies.

Another fertility complication with Hashimoto’s is a high risk of polycystic ovary syndrome (PCOS). In PCOS, a hormonal imbalance makes you stop ovulating, so you can’t get pregnant. It is treatable, though. Your OB-GYN can help you find treatments that get ovulation going again.

Hashimoto’s and Gestation

Untreated or undertreated Hashimoto’s can lead to problems during pregnancy, which can affect both you and your baby. Hashimoto’s disease increases your risk of:

  • Preeclampsia
  • Anemia
  • Miscarriage
  • Placental abruption

Preeclampsia

Preeclampsia is high blood pressure during pregnancy. It usually comes on late in your pregnancy, and it can damage your organs and cause:

  • Growth problems in the baby
  • Premature birth
  • Stillbirth 

Symptoms of preeclampsia that you can watch for include:

  • Swelling in the face and hands
  • Headache
  • Blurry vision
  • Upper right abdominal pain

If you develop preeclampsia, the safest thing for you is to deliver the baby. But that’s often not the safest option for the baby. Much of the treatment depends on how far along you are:

  • If you’re 37 weeks or more along: Your baby will likely be delivered right away. That’s especially true if the illness is severe.
  • If you’re less than 37 weeks along: Your doctor will try to delay inducing labor. You may be put on bed rest or admitted to the hospital for monitoring.

You may be given corticosteroid medications to speed up your baby’s lung development. That can help if the baby has to be delivered early. Your doctor will try to avoid it, but if your health is seriously in danger, the baby may have to be delivered prematurely.

Anemia

Anemia involves low red blood cells or hemoglobin (an important protein in the blood). It can:

  • Impair your immune system
  • Increase the risk of blood loss during labor
  • Increase the risk of premature birth or low birth weight

Usually, anemia symptoms don’t show up until your cell counts are really low. They can include:

  • Pale skin, lips, or nails
  • Fatigue
  • Dizziness
  • Trouble concentrating
  • Difficulty breathing
  • Rapid heartbeat

The main treatment for anemia is iron supplements. Your doctor may also tell you to eat a diet rich in iron. For very low levels, treatment may include:

Miscarriage

Doctors have long known Hashimoto's is linked to miscarriage. That's partly due to a thyroid hormone imbalance. Levels of testosterone and estradiol (a type of estrogen) are often low.

Recently, researchers have found a tie between miscarriage and immune dysfunction. For a long time, doctors didn’t know why the body treated a fetus differently from a transplanted organ because they’re both “foreign” tissues in your body. Then they discovered that during pregnancy, a healthy immune system switches off the part of the immune system that attacks foreign bodies.

In Hashimoto’s, studies suggested that process doesn’t happen properly. Researchers suspect this makes your body reject the baby as foreign. However, experts don’t yet fully understand how this works.

Common symptoms of a miscarriage include:

  • Vaginal bleeding that goes from light to heavy
  • Back pain
  • Abdominal pain and cramping

Not all bleeding in the first trimester signals a miscarriage. Still, to be on the safe side, see your doctor if you bleed during any stage of pregnancy.

Some research shows that proper thyroid treatment before pregnancy can lower miscarriage risk. But it's not clear whether hormone levels during pregnancy have an effect. Several treatments that affect the immune system have been suggested. So far none is proven effective at reducing the Hashimoto’s-related miscarriage risk. These treatments include:

If you begin having signs of a potential miscarriage, your doctor may suggest:

  • Being put on bed rest
  • Avoiding penetrative sex
  • Using ultrasound to check for any visible problems
  • Performing blood work to test pregnancy hormone levels

Placental Abruption

The placenta is your baby's lifeline. It delivers nutrients and oxygen from your blood into the baby's. In a placental abruption, the placenta pulls away from your uterus before childbirth. It’s most common in the third trimester. But it can happen anytime in the second half of your pregnancy. 

The abruption takes away the baby's blood and oxygen. That can lead to premature delivery. In rare cases, it causes stillbirth. It can also make you lose a lot of blood. A moderate or severe abruption is a life-threatening emergency for you and your baby.

Symptoms of a placental abruption include:

  • Vaginal bleeding, which may be light or heavy
  • Cramps and belly pain or tenderness
  • Painful contractions
  • More or less movement from the baby

Doctors can't reattach your placenta after an abruption. Sometimes the problem repairs itself. Your treatment depends on the severity and how far along you are:

  • Mild abruption: You’ll probably be admitted to the hospital for a short time. If you and your baby aren’t in distress, you may just need a few days of bed rest and close monitoring. 
  • Moderate abruption: You'll probably stay in the hospital for the rest of your pregnancy. You may need a blood transfusion. If your baby is in distress, labor may be induced early. 
  • Severe abruption (total separation): Your baby will need to be delivered right away. Stillbirth is rare but possible. A blood transfusion is more likely.

Studies have shown that levothyroxine treatment has little to no effect on your risk of placental abruption. Levothyroxine is a medication used to treat hypothyroidism.

Always call your doctor or get emergency medical help for vaginal bleeding, abdominal pain, and painful contractions during pregnancy.

Hashimoto’s and Postpartum

Your thyroid disorder can affect you after your baby is born. That period is called postpartum.

Postpartum Hemorrhage

Hashimoto’s disease puts you at risk for heavy bleeding after delivery. This is called postpartum hemorrhage. It can happen within 24 hours of giving birth. It's most common when you're delivering the placenta.

Contractions that help deliver the placenta put pressure on the blood vessels attached to it. That makes them stop bleeding. However, when contractions aren’t strong enough, the blood vessels continue to bleed. That causes a hemorrhage. Tears in other organs or clotting problems can also cause postpartum hemorrhage.

Signs of postpartum hemorrhage are:

  • Uncontrolled bleeding
  • Drop in blood pressure
  • Increased heart rate
  • Drop in red blood cell count
  • Sometimes swelling and pain in the vagina

Most of the time, you'll still be in the hospital during the most likely time for a hemorrhage. That's especially true if you've had a cesarean section. However, it can happen after you've gone home.

Treatment of postpartum hemorrhage is aimed at stopping the bleeding as quickly as possible. It may include:

  • Medications to clot the blood
  • Uterine massage to trigger contractions
  • Repair of damaged tissues
  • Tying off or sealing blood vessels
  • Use of devices that apply pressure to the bleeding area
  • Surgically opening the abdomen to find the source of the blood
  • As a last resort, a hysterectomy (surgical removal of the uterus)

Impact on Recovery

Your doctor should continue monitoring your thyroid levels after your baby is born. This is especially true if your levothyroxine dosage increased during pregnancy. 

Pregnancy shouldn't have a long-term effect on the severity of your Hashimoto's. Most people eventually go back to their pre-pregnancy dosage.

Let your doctor know if you have symptoms that could point to high thyroid levels due to overmedicating. Those can include:

  • Nervousness
  • Irritability
  • Weakness
  • Trouble tolerating heat
  • Tremor
  • Rapid, irregular heartbeat
  • Mood swings
  • Diarrhea or frequent bowel movements
  • Goiter (swelling in the front of your throat, trouble breathing or swallowing)

Breastfeeding

Hashimoto’s disease shouldn’t affect your ability to breastfeed. Small amounts of levothyroxine may get into your breast milk. It’s believed to be safe for your baby, though.

How Commonly Is Hashimoto’s Diagnosed During Pregnancy?

Hashimoto’s is diagnosed during 2% to 3% of pregnancies. Symptoms include fatigue, muscle cramps, severe constipation, memory or concentration problems, and cold intolerance. Since some of those can also be pregnancy symptoms, it can be hard to spot a new case of Hashimoto's.

Summary

Hashimoto’s disease can make it hard to get pregnant and lead to serious pregnancy complications, including preeclampsia, anemia, miscarriage, and placental abruption. Having good thyroid hormone levels before pregnancy can lower your risk of some problems. After delivery, you may be at risk of postpartum hemorrhage. Your doctor will closely monitor your health and Hashimoto's treatment during and after pregnancy.

A Word From Verywell

Facing a pregnancy with Hashimoto’s disease can be scary. The risks are serious and shouldn’t be ignored. However, keep in mind that most people with Hashimoto’s have successful pregnancies and healthy babies. Watch your health, stick with your treatment regimen, and let your doctor know about any problems or concerns. That'll give you the best chance of avoiding complications and delivering a healthy baby.

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Article Sources
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Additional Reading
  • U.S. Department of Health & Human Services, Office on Women’s Health. Hashimoto’s disease. Updated October 18, 2018.