Can Birth Control Affect Your Thyroid?

The thyroid is a small gland at the base of your neck that has an enormous impact on your overall health. This important gland produces thyroid hormones that regulate your metabolism, heart rate, mood, and more.

So when something disrupts thyroid function, it can throw off many vital processes in the body. This leads many women to ask: can my birth control pill be messing with my thyroid?

Can Birth Control Affect Your Thyroid Function?

Research indicates that estrogen-containing birth control pills can potentially impact thyroid function in some women. Here’s how:

  • Estrogen increases levels of thyroid binding globulin (TBG), a protein that binds to thyroid hormone. This means you have more T3 and T4 bound to TBG, leaving less “free” hormone circulating in the bloodstream. It’s the free T3 and T4 that actually enter your cells and exert effects on the body.
  • With more thyroid hormone bound to TBG, there’s a decrease in free T4 levels. Even small changes in free T4 can affect TSH levels.
  • Over time, the pituitary senses less thyroid hormone is available and TSH rises to try to stimulate more production. Elevated TSH is the hallmark of hypothyroidism.

For these reasons, long-term use of estrogen-containing contraceptives may increase the risk of an underactive thyroid. However, more research is still needed.

Signs of Thyroid Trouble

If your thyroid function is impaired, you may notice one or more of the following symptoms:

  • Fatigue, weakness, or sluggishness
  • Unexplained weight gain or difficulty losing weight
  • Constipation
  • Dry, thinning hair and skin
  • Feeling cold when others are warm
  • Heavy or irregular menstrual periods
  • Depression, anxiety, and moodiness
  • Reduced concentration and memory
  • Muscle cramps, aches, and weakness
  • Sleep disturbances

Keep in mind these symptoms can also result from many other causes. Blood tests are needed to determine if hormone imbalances due to hypothyroidism are to blame.

Monitoring Your Thyroid on Birth Control

If you take estrogen-containing contraceptives, it’s wise to have your thyroid periodically checked with blood tests. This includes:

  • TSH level – The ultrasensitive TSH test can detect even subtle imbalances.
  • Free T4 – Measures unbound thyroid hormone available to your tissues.
  • Thyroid antibodies – Elevated levels can indicate autoimmune thyroid disease.

Ideally, get baseline thyroid tests done before starting hormonal birth control. Once on birth control, most experts recommend testing TSH and free T4 every 6 to 12 months. This allows early detection of any thyroid dysfunction.

If tests reveal thyroid imbalance, your doctor may adjust medication dosage if needed. Or you can discuss alternative birth control methods that don’t affect thyroid function.

Impact of Thyroid Dysfunction on Fertility and Pregnancy

Thyroid issues can affect the reproductive system and fertility in various ways. An underactive thyroid may cause:

  • Irregular periods – Thyroid hormones influence the menstrual cycle. Missing or irregular periods can result from low thyroid levels.
  • Ovulation problems – Hypothyroidism can disrupt signals from the pituitary that trigger ovulation. Without ovulation, pregnancy can’t occur.
  • Higher prolactin – This hormone inhibits ovulation when elevated.

Birth control pills also influence hormones that control ovulation and menstruation. The combined effects on fertility from both hypothyroidism and hormonal birth control can be complex. Therefore, optimizing thyroid function is an ideal preconception.


Non-Hormonal Birth Control Options

For women prone to thyroid issues, non-hormonal contraceptive methods are an ideal choice. Effective hormone-free options include:

  • Copper IUD – Paragard IUD provides long-acting birth control without hormones.
  • Natural family planning – Track ovulation patterns to avoid sex during fertile days.
  • Spermicide – Blocks sperm from reaching the egg.
  • Tubal ligation – Permanent method where fallopian tubes are closed off.

Talk to your healthcare provider about the pros and cons of non-hormonal birth control methods compared to hormonal options.

Lifestyle Tips for Thyroid Health

While some effects of birth control pills can’t be controlled, you can take charge of your thyroid and overall health through lifestyle:

  • Choose nutritious whole foods – An anti-inflammatory diet rich in fruits, veggies, lean proteins, and healthy fats provides nutrients that support thyroid function. These include selenium, zinc, B vitamins, vitamin D, omega 3s, and antioxidants. Avoid heavily processed foods when possible.
  • Reduce stress – Chronic stress takes a toll on the thyroid. Make time for relaxing activities like yoga, meditation, massage, and deep breathing. Get adequate sleep and rest.
  • Stay active – Exercise and movement help circulation, lower inflammation, and balance hormones. Aim for 30-60 minutes per day.
  • Minimize toxins – Things like cigarette smoke, chemicals, and plastics can disrupt your endocrine system. Use safe personal care and household products whenever possible.


Long-term use of estrogen birth control pills may potentially contribute to thyroid dysfunction in some women. However, there’s still more research needed to clarify the degree of risk, contributing factors, and who is most susceptible.

If you take hormonal contraceptives, get in the habit of having your thyroid levels tested once or twice per year. Report any potential symptoms of hypothyroidism to your doctor promptly. Don’t hesitate to ask about alternatives like non-hormonal birth control if thyroid issues develop.

With awareness and early detection, the impact of birth control pills on your thyroid can likely be well managed. Open communication with your healthcare provider is key to balancing contraception needs with optimal thyroid health.

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