Thyroid Disease Reproductive Health How Thyroid Function Affects Menstruation Menstrual irregularities are more common in severe thyroid disease By Mary Shomon Mary Shomon Facebook LinkedIn Twitter Mary Shomon is a writer and hormonal health and thyroid advocate. She is the author of "The Thyroid Diet Revolution." Learn about our editorial process Updated on November 18, 2021 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Do-Eun Lee, MD Medically reviewed by Do-Eun Lee, MD LinkedIn Do-Eun Lee, MD, has been practicing medicine for more than 20 years, and specializes in diabetes, thyroid issues and general endocrinology. She currently has a private practice in Lafayette, CA. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Hypothyroidism vs. Hyperthyroidism Heavy Menstruation Absent or Infrequent Menstruation Decreased Fertility The thyroid gland is a small butterfly-shaped gland located at the base of the front of your neck. It plays an essential role in your reproductive health, directly affecting your ovaries and indirectly interacting with sex hormone-binding globulin (SHBG), a protein that "sticks" to reproductive hormones so they can be carried throughout your body. Given this, thyroid dysfunction can result in menstrual irregularities. However, menstrual problems tend to be more common in those with severe thyroid disease versus those with more mild or moderate cases. If you are experiencing unusual menstrual symptoms, it's worth asking your healthcare provider to evaluate your thyroid. This article explains why and covers some of the most common menstrual symptoms related to thyroid disorders, plus what you can do about them. Brianna Gilmartin / Verywell Hypothyroidism vs. Hyperthyroidism Problems with your menstrual cycle may be due to an underactive or overactive thyroid. How symptoms present could depend on which type of thyroid disorder you have. Hypothyroidism Hypothyroidism, or an underactive thyroid gland, occurs when the body produces too little thyroid hormone. There are several menstrual problems associated with hypothyroidism, including: Heavy menstrual bleedingFrequent menstrual bleedingInfrequent cyclesAbsent menstrual cycles Hyperthyroidism Hyperthyroidism is a disorder of an overactive thyroid gland. That means your body produces too much thyroid hormone. Menstrual abnormalities seen with hyperthyroidism include: Absent or infrequent periods: This is the most common symptom seen with severe hyperthyroidism. Too much thyroid hormone leads to increased SHBG, which can prevent ovulation. Light and short periods: Bleeding may be less than typical—and brief. Decreased fertility: Not ovulating can impact your fertility. Risk of miscarriage: In addition, excessive thyroid hormone production during pregnancy increases the risk of miscarriage. Treatment with an antithyroid drug can help prevent menstrual and fertility problems. Another option is radioactive iodine (RAI) therapy, which shrinks the thyroid. However, this treatment is not safe during pregnancy. Recap Too little thyroid hormone can cause heavy menstrual bleeding, while too little thyroid hormone can have the opposite effect. Both thyroid conditions can cause missed or no periods and affect fertility. Heavy Menstruation The American College of Obstetricians and Gynecologists (ACOG) defines heavy menstrual bleeding as one or more of the following: Bleeding that lasts more than seven daysBleeding that soaks through one or more tampons or pads every hour for several hours in a rowNeeding to wear more than one pad at a time to control menstrual flowNeeding to change pads or tampons during the nightMenstrual flow with blood clots that are as big or bigger than a quarter Keep in mind, while hypothyroidism is one potential cause of heavy bleeding, there are many other possible causes, including: Infection Medication side effects Fibroids Polycystic ovary syndrome (PCOS) Uterine cancer Be sure to see your OB/GYN if you are experiencing heavy periods. To help with diagnosis, they may want to perform some tests such as a: Pelvic examination Transvaginal ultrasound: Imaging done by inserting a wand into the vagina so that images of your reproductive organs can be transmitted onto a monitor Thyroid-stimulating hormone (TSH) blood test Recap Hypothyroidism and some other medical conditions can cause heavy periods. To determine the cause, your doctor may need to do a pelvic exam, ultrasound, and bloodwork. Absent or Infrequent Menstruation Hypothyroidism can also lead to absent periods (amenorrhea) or infrequent periods (oligomenorrhea). Irregular periods are more common. Absent or infrequent cycles can occur from high thyroid releasing hormone (TRH) in people with hypothyroidism. The high TRH levels trigger the pituitary gland (a pea-sized organ located at the base of the brain) to release prolactin. Too much prolactin interferes with the ability of the ovaries to produce estrogen. Reduced estrogen can lead to some reproductive health symptoms and issues, including: Infrequent periods Absent periods Abnormal milky discharge from the breasts (galactorrhea) Hot flashes Vaginal dryness Infertility Recap Thyroid problems can cause your period to stop altogether or to occur infrequently. That's because high TRH triggers prolactin production. Too much prolactin interferes with the ovaries' ability to produce estrogen, thereby interfering with your menstrual cycles. Decreased Fertility Since a lack of thyroid hormone can prevent ovulation, having hypothyroidism can make it difficult to get pregnant. Moreover, people with hypothyroidism who are pregnant have an increased risk of miscarrying during the first trimester. The upside is that treatment with thyroid hormone replacement medication (levothyroxine) may improve fertility and lower the risk of pregnancy loss. That said, some people who use thyroid medication continue to experience abnormal periods. How Do Thyroid Problems Affect Fertility and Pregnancy? Summary Thyroid conditions can have an impact on your menstrual cycles. Symptoms may range from heavy and frequent periods to irregular and absent cycles. These symptoms are due to how thyroid hormones impact reproductive hormone production. As such, menstrual irregularities could also affect fertility and pregnancy. A Word From Verywell While a change in your menstrual cycle may be the first indication of a thyroid disorder, remember that there are many other potential causes. It's always best to contact your healthcare provider for an evaluation so the underlying cause can be confirmed. Was this page helpful? Thanks for your feedback! Losing weight with thyroid disease can be a struggle. Our thyroid-friendly meal plan can help. Sign up and get yours free! Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 4 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Gude D. Thyroid and its indispensability in fertility. J Hum Reprod Sci. 2011 Jan-Ape;4(1):59-60. doi:10.4103/0974-1208.82368 Kakuno Y, Amino N, Kanoh M, Kawai M, Fujiwara M, Kimura M, et al. Menstrual disturbances ijn various thyroid diseases. Endocr J. 2010;57(12):1017-22. doi:10.1507/endocrj.K10E-216 Saran S, Gupta BS, Philip R, Singh KS, Bende SA, Agroiva P, et al. Effect of hypothyroidism on female reproductive hormones. Indian J Endocrinol Metab. 2016 Jan-Feb; 20(1):108-13. doi:10.4103/2230-8210.172245 American College of Obstetricians and Gynecologists. Frequently asked questions. Gynecologic problems. Heavy menstrual bleeding.