Thyroid Disease Reproductive Health How Thyroid Function Affects Menstruation Menstrual irregularities are more common in severe thyroid disease By Mary Shomon Mary Shomon Verywell Health's Facebook Verywell Health's LinkedIn Verywell Health's 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 June 21, 2022 Medically reviewed by Do-Eun Lee, MD Medically reviewed by Do-Eun Lee, MD Verywell Health's 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 Thyroid problems can result in menstrual irregularities. This is because the thyroid gland, a small butterfly-shaped gland located at the base of the front of your neck, plays an essential role in your reproductive health. The thyroid directly affects your ovaries and indirectly interacts with sex hormone-binding globulin (SHBG). SHBG is a protein that "sticks" to reproductive hormones so they can be carried throughout your body. Menstrual problems tend to be most common in those with severe thyroid disease and less common in 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 thyroid disorders can cause menstrual irregularities. It also covers some of the most common menstrual symptoms related to thyroid disorders, plus what you can do about them. Verywell / Brianna Gilmartin 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 bleeding: This is a common symptom in many people with hypothyroidism.Frequent menstrual bleeding: People with hypothyroidism may also have menstrual periods that last longer or occur more often than people without the condition.Infrequent cycles: Hypothyroidism may also cause you to miss periods or have them less often.Absent menstrual cycles: Some people with hypothyroidism may not menstruate.Infertility and miscarriage: People with untreated hypothyroidism may have trouble conceiving and are more likely to experience miscarriage and pregnancy complications. The first-line treatment for hypothyroidism is the thyroid hormone replacement medication Levoxyl (levothyroxine). This medication has been shown to improve menstrual problems even in people with normal thyroid function. That said, some people who use thyroid medication continue to experience abnormal periods. 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.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 regulate thyroid function and alleviate these menstrual and fertility problems. Another option is radioactive iodine (RAI) therapy, which shrinks the thyroid. However, this treatment is not safe during pregnancy. 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 Absent or Infrequent Menstruation Hypothyroidism and hyperthyroidism 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 In people with hyperthyroidism, too much thyroid hormone leads to increased SHBG, which can prevent ovulation. Decreased Fertility Since a lack of thyroid hormone can prevent ovulation, having thyroid problems can make it difficult to get pregnant. Hyperthyroidism may also cause early menopause, or menopause that occurs before or around the age of 40. Moreover, people with hypothyroidism or hyperthyroidism who are pregnant have an increased risk of miscarrying. For people with hypothyroidism, treatment with levothyroxine may improve fertility and lower the risk of pregnancy loss. People with hyperthyroidism are often treated with antithyroid medication during the second half of pregnancy. Because these medications cross the placenta, however, their use needs to be carefully monitored by a healthcare provider. Fertility and Pregnancy Challenges With Thyroid Disease 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. 8 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 Vissenberg R, Van den Boogaard E, Van Wely M, et al. Treatment of thyroid disorders before conception and in early pregnancy: a systematic review. Hum Reprod Update. 2012;18(4):360-73. Jamilian M, Talaei A, Chehrei A, Rezvanfar MR, Rafei F. The study of the effect of levothyroxine on dysfunctional uterine bleeding (DUB) in euthyroid women. ISMJ. 2017;20(4):317-25. Saran S, Gupta BS, Philip R, 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. Johns Hopkins Medicine. Thyroid disorders in women. Andersen SL, Laurberg P. Managing hyperthyroidism in pregnancy: current perspectives. Int J Womens Health. 2016;8:497-504. doi:10.2147/IJWH.S100987 doi:10.2147%2FIJWH.S100987 By Mary Shomon Mary Shomon is a writer and hormonal health and thyroid advocate. She is the author of "The Thyroid Diet Revolution." See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit