Can a New Mother Breastfeed While Hypothyroid?

Mother breastfeeding baby girl in bedroom
Most women who are hypothyroid and taking thyroid hormone replacement can safely breastfeed. Antenna/Getty

Congratulations on having a new baby! As a new mother, you may want your new baby to have the many proven benefits of breast milk, vs. formula. But breastfeeding mothers are also told to be careful about taking drugs and medications, as well as receiving certain medical treatments while nursing. This FAQ answers your key questions regarding breastfeeding if you are diagnosed with or being treated for thyroid disease -- including hypothyroidism and hyperthyroidism -- while you are also nursing your new baby.

Question: Can a New Mother Breastfeed While Hypothyroid?

If you are a new mother, and you are hypothyroid, and taking thyroid hormone replacement drugs, is it safe to breastfeed?

What are the concerns or issues that you may face?

Answer: Yes. There's no reason why a woman who is hypothyroid and on thyroid hormone replacement shouldn't or can't breastfeed under normal circumstances.

If you are hypothyroid, and taking an optimal dose of thyroid replacement medication, you should be able to breastfeed your baby normally. (You can read more about taking thyroid hormone replacement medications when you are breastfeeding here.) 

It's actually crucial that you continue your thyroid hormone medications. It is important to treat hypothyroidism when you are breastfeeding. Without proper thyroid treatment, you may not be able to establish a healthy supply of breast milk for your new baby. An underactive thyroid -- hypothyroidism -- can also contribute to a difficult let-down reflex. However, once your thyroid is optimally treated, these issues should be resolved.

(Here are some other reasons -- beyond thyroid conditions -- that can affect your milk supply negatively.) 

Keep in mind, however, that in some women, the hormonal shifts that occur right after delivery can cause a rapid change in thyroid function that can interfere with your ability to nurse, including milk supply. 

Thyroid function is also related to your prolactin levels. Prolactin is the hormone that helps you produce milk.

So some women who are hypothyroid may find that they are unable to produce enough milk to ensure healthy growth in their newborn.

If you are new mother with preexisting hypothyroidism, you should have a thyroid evaluation within a few weeks of delivery at latest. This checkup will look for changes in your thyroid function that may warrant a change in your medication dosage.

If you are hypothyroid, and your nursing baby is losing weight, slow to gain weight, or isn't having the requisite number of bowel movements and wet diapers, you should request a thorough thyroid evaluation right away, and talk to your pediatrician about options to ensure that your baby is getting enough nutrition. (Here are five signs that you producing enough milk for your baby.) 

If you are having problems with low milk supply, consider consulting a lactation consultant, or your pediatrician, for advice on medications and natural remedies that can help improve your milk supply

Need more help? Read these tips for breastfeeding during your baby's first 6 weeks.

Read more Frequently Asked Questions About Breastfeeding and Thyroid Disease

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