Thethyroid glandis a butterfly-shaped organ located in the lower part of your neck.
This gland is part of the endocrine system and plays an essential role in women’s health.
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How Does Birth Control Affect the Thyroid?
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The estrogen in most hormonal birth control can alter how thyroid hormones are made, used, and converted.
Estrogen increasesthyroid-binding globulins(TBG), which prevents thyroid hormones from freely circulating in your blood.
It can also influence iodine uptake.
This is significant becauseiodine deficiencyis the leading cause of hypothyroidism.
Research suggests that longtime use of hormonal birth control is strongly associated with hypothyroidism.
This is especially true for those who have taken hormonal birth control for over 10 years.
A healthcare provider may still advise you to take hormonal birth control if you have hypothyroidism.
However, they may want to increase your dose of thyroid medication and monitor you more closely.
Nonhormonal Birth Control Methods
A healthcare provider may recommend birth control methods that dont include hormones.
Healthcare providers diagnose and monitor hypothyroidism by symptoms and blood test results.
Theseblood testsinclude thyroid-stimulating hormones (TSH), triiodothyronine (T3), and thyroxine (T4).
Thepituitary glandproduces the TSH that helps your thyroid gland release T3 and T4.
When T3 and T4 levels are low, the pituitary makes more TSH.
High levels of TSH and low levels of T4 often indicate hypothyroidism.
Estrogen can increase the T3 and T4 levels.
However, the TSH typically stays within the normal range.
T3 Levels
T3 levels are the last to become abnormal.
They are more useful when diagnosing hyperthyroidism rather than hypothyroidism.
Can Hypothyroidism Affect the Effectiveness of Birth Control?
Tips for Taking Thyroid Medication
Thyroid medications are prescribed in tiny doses.
Small changes, including switching brands, can affect how they work.
Simultaneously taking other medications or eating can decrease absorption.
Otherwise,stopping birth controlcan be done safely at any time.
You may notice some menstrual irregularities or spotting between periods.
This is typically temporary and resolves within a few months.
Remember that you’re free to get pregnant as soon as you stop taking birth control.
If you do become pregnant, notify a healthcare provider.
They may want to adjust your thyroid medication dose and monitor thyroid levels to promote a healthy pregnancy.
However, correcting thyroid hormone levels with medications often resolves this issue.
Summary
Hypothyroidism is a disorder where the thyroid doesnt produce enough hormones.
Estrogen, a hormone in most hormonal birth control, can alter how thyroid hormones are produced and work.
Long-term use (over 10 years) of hormonal birth control increases your risk of hypothyroidism.
However, it does not typically affect TSH levels.
you’ve got the option to still take birth control if you have hypothyroidism.
However, a healthcare provider may want to increase your dose of thyroid medication and monitor you more closely.
A Word From Verywell
Many women take hormonal birth control at some point in their life.
The thought of it leading to hypothyroidism can be concerning.
Keep in mind that the risk is small and usually only results from long-term use.
Talk with a healthcare provider if you are concerned about your specific situation.
They can also discuss nonhormonal birth control options if that is best for you.
Its best to leave a four-hour window between them.
A healthcare provider may want to adjust your thyroid medication when you start or stop hormonal birth control.
Untreated hypothyroidism can increase your risk of infertility (not getting pregnant).
However, your chances of getting pregnant increase when thyroid levels are corrected through medication.
Infertility is a common problem for women with hypothyroidism, especially when untreated.
One study showed a 23.9% rate of infertility among women who had hypothyroidism.
However, many of these women got pregnant six weeks to a year after starting thyroid medication.
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