Can Thyroid Hormone Levels Affect Breastfeeding?

Can Thyroid Hormone Levels affect Breastfeeding?

No one wants to deal with thyroid problems, especially if you are a woman. Unfortunately, you cannot always choose the hand you are dealt, but you can get certain conditions under control. Now that you have bundle of joy to fuss over, you might be worried that your thyroid condition could hurt your baby in some way.

One of those ways would be through breastfeeding. Thyroid hormones have an important role in milk production and breast development in woman. Any lack of hormones can create difficulties during breastfeeding, just as an excess of hormones invites challenges.

Today, we aim to answer your questions related to thyroid problems and breastfeeding. Let’s get started.

Can I breastfeed with thyroid problems?

The simple answer is yes. Of course you can. It will not always be easy or comfortable, however; and that is where the problem begins. Many mothers notice that their milk supply is affected in some way, depending on the type of thyroid condition they struggle with.

Prolactin, a hormone you are probably familiar with, is affected by thyroid hormone production. Thyroid-releasing hormone (TSH) also stimulates prolactin secretion in the pituitary gland. Whenever you have a thyroid issue, you can expect prolactin levels to drop exponentially (or rise, if you have an overactive thyroid).

The let-down reflex also slows due to thyroid complications, so less milk is released from the breasts, even when they are engorged.

Luckily, thyroid medications are safe for nursing mothers to use. You just have to know which thyroid condition is affecting you and how you go about getting the issue under control.

What are common thyroid problems?

Let’s have a look at some common thyroid conditions that may affect mothers and their nursing babies.

What is Hypothyroidism?

Also known as “under-active thyroid,” hypothyroidism is when the gland does not produce enough of the hormones triiodothyronine (T3) and thyroxine (T4) to support normal functions within the body. Women who struggle with hypothyroidism will find that their breastmilk production struggles to refresh during feeds. The let-down reflex is also inhibited, so breastfeeding can become difficult and uncomfortable.

Symptoms of hypothyroidism include:

  • Chronic fatigue
  • Sudden weight gain
  • Poor mood and depression
  • Cold intolerance
  • Prolonged, heavy periods
  • Absence of periods in women in their reproductive years
  • Dry skin
  • Constipation
  • Hair loss
  • Changes in voice
  • Low breastmilk supply and decreased milk production for lactating women

You may notice that many of these symptoms can be affiliated with other disorders, such as postpartum fatigue and postpartum depression. If you have ruled out these issues, you should certainly speak with your doctor about getting a thyroid test done.

That said, no harm will come from breastfeeding if you are currently undergoing thyroid replacement therapy. Oftentimes, the medication that is prescribed to mothers with hypothyroidism is not secreted in breastmilk, and if so, the quantity is negligible. Once the deficiency in T3 and T4 is corrected, the symptoms start to dissipate, and you will feel better.

What is Hyperthyroidism?


The opposite of under-active thyroid is hyperthyroidism, or “overactive thyroid.” With this condition, the thyroid gland excretes too much T3 and T4 hormones and excites the body. When a woman has hyperthyroidism, she experiences an overabundance of breastmilk. Unfortunately, this is coupled with an impaired let-down reflex, causing complications during breastfeeding.

Symptoms of hypothyroidism include:

  • Chronic fatigue and insomnia
  • Enlarged gland in the neck
  • Sweating
  • Unexpected weight loss
  • Tremors
  • Anxiety
  • Heart palpitations
  • Heat intolerance
  • Light or absent menstrual flow
  • Diarrhea
  • Increased or rapid resting pulse
  • Excessive breastmilk production in lactating women

If you have not experienced any issues with your thyroid prior to giving birth, you might have developed a mild form of hyperthyroidism that will persist for the first few months. The hyperthyroidism will then shift into hypothyroidism, and that can eventually lead to postpartum thyroiditis, which is discussed below.

One of the struggles of hyperthyroidism is weight loss and poor nutrition. Since breastfeeding requires mothers to eat an extra 500 calories a day, any rapid drop in weight can cause complications for both the mother and her child.

What is Postpartum thyroiditis?

As the name suggests, postpartum thyroiditis is the inflammation of the thyroid that occurs within the first year of giving birth. Typically, postpartum thyroiditis happens when the individual already suffers from hypo- or hyperthyroidism. The condition happens after 5-7-percent of pregnancies throughout the world.

Postpartum thyroiditis is often mild in the beginning, and the symptoms can be difficult to diagnose. Depending on which phase the condition is in, treatment will have to be adjusted.

Most mothers suspect they have a problem when their milk supply is poor, even several months into breastfeeding. This is often when they find out they have an inflamed thyroid gland.

Thyroid cancer

The most troubling and dangerous condition would be thyroid cancer. In the early stages, the only symptoms are often difficulty swallowing, hoarseness, coughing, and an unrelenting pain in the neck.

Thyroid cancer can be problematic for both you and your baby. Not only does the cancer affect thyroid functioning, you will oftentimes need to undergo chemotherapy or take radioactive iodine pills. Sometimes, surgery is necessary. None of this is recommended for breastfeeding mothers, so you will most likely have to switch to formula.

Can you take thyroid medications while breastfeeding?

Those who are already on thyroid medication will know this one truth: thyroid conditions need immediate treatment. As soon as you experience one or more of the symptoms that have been discussed, you should get an appointment with your general physician.

If you refuse to get treated for your medical condition, whether it is related to your thyroid function or not, is putting you and your child in harm’s way. Never risk your life or your baby’s life—especially when the medications you receive for hyperthyroidism and hypothyroidism will have little to no impact on your baby.

The medications for hypothyroidism are considered safe for use during pregnancy and breastfeeding, because the medication works like the hormones should. The same stands for hyperthyroidism.

The only time you should be concerned is if you have thyroid cancer and need to take radioactive iodine or are getting surgery.

Now, you might be wondering what would happen if you took too much thyroid medication. Overdosing on thyroid hormones will put you into a hypermetabolic state, increasing your heart rate and causing frequent bowel movements. This can cause you some discomfort, so be careful with your doses.

Can tests be taken during breastfeeding to check thyroid condition?

When you are scheduled to get a thyroid exam, the first thing to cross your mind will probably be what the lingering effects are. Thyroid scans are frequently conducted to check for Graves’ disease or postpartum thyroiditis but with one caveat.

Because a thyroid scan requires the use of radioactive iodine, this test is not recommended for breastfeeding mothers. Radioactive iodine will pass through the body into the breastmilk and will concentrate in the baby’s thyroid.

If you are nursing, you can ask for an alternative, such as technetium, a synthetic chemical that is much safer for breastfeeding mothers than radioactive iodine. Other procedures may be available. Speak to your doctor for more options.

Tips for Breastfeeding with thyroid problems

Let’s have a look at some ways to make balancing thyroid treatments and breastfeeding a little less complicated.

Tips related to hypothyroidism are:

  • Be sure to visit your doctors regularly and listen to them, because they will know how to help you management the condition and prevent any side effects that could affect breastfeeding.
  • Since you will have difficulty producing milk for a while, consider using galactagogues or herbal supplements that can stimulate lactation, such as fennel, fenugreek, and milk thistle.
  • Take your medication that was prescribed for you. Levothyroxine, which is solely for hypothyroidism, will not affect you or your child adversely.
  • Be sure to maintain a balanced diet and drink plenty of water throughout the day.
  • Stimulate milk production by using a breast pump after your feed your baby. Using a pump between feedings can help bolster milk production.
  • If you are concerned about your baby, talk to your doctor about tests for thyroid hormone imbalance.

Tips related to hyperthyroidism are:

  • If you are on an antithyroid medication, such as Tapazole (methimazole) or PTU (propylthiouracil), you are save to take them while you are nursing. The active ingredients do not pass into breastmilk. Simply take your medication after you have fed your baby.
  • Avoid stress as much as possible.
  • Do not smoke. Tobacco will worsen the symptoms of hyperthyroidism, and the effects of smoking are also terrible for your baby.
  • Since hyperthyroidism can cause an excess of milk, your breasts can easily become engorged. Be sure to wear a decent bra, pump often, and save the milk. Use a cold compress on your breast to help with pain.
  • Sometimes, your doctor may recommend that you need surgery to remove a piece of your thyroid glance. You will be separated from your child during this time, but you will be able to return to breastfeeding—if that is your choice—after you have convalesced enough.


If you are struggling with producing milk or have an excess of milk but cannot expel it with ease, you could have a thyroid problem. Breastfeeding during a thyroid problem is perfectly safe for you and your child, so do not delay in seeking medical care, especially if your breastfeeding struggles are paired with other symptoms mentioned in this article.

Have further questions about breastmilk production and breastfeeding? Get in touch with us by filling out the contact form.

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