Thyroid and Infertility


If you have thyroid issues, especially if they’re untreated, they can affect your fertility. Whether you have low thyroid function – hypothyroid – or too-high function – hyperthyroid – your fertility may be affected.

Low thyroid function can cause your reproductive hormones to become imbalanced. This might make your periods irregular. Even if your periods are regular, you may not be ovulating. You can test to see if you are ovulating by using an ovulation predictor kit around the time that you think you may be ovulating. This test measures the level of luteinizing hormone, or LH, in your body: LH stimulates your ovaries to release an egg. With diligent testing, you can soon find out whether or not you’re ovulating.

If you are indeed ovulating, hypothyroid can still cause you problems – you may have a short luteal phase. The luteal phase occurs between ovulation and menstruation, and is the time when the fertilized egg will implant itself in the uterine wall. It should be around 13 to 15 days. If this phase is too short, the egg doesn’t have enough time to implant before the uterine lining sheds and the menstrual period begins.

It’s not known exactly how hypothyroid interferes with fertility, but it’s thought that it increases prolactin, a hormone that’s produced by the pituitary gland and that causes new moms to lactate. Just like it does in new moms, prolactin can stop ovulation and halt the monthly period. The increase in prolactin may be caused by an excess of another hormone, TRH, which stimulates the pituitary gland to produce prolactin.

Hyperthyroidism can also affect fertility. Women with this disorder may have irregular or absent periods. They’re also more likely to have miscarriages. If a woman with untreated hyperthyroidism does get pregnant and carry the baby to term, the risks of birth defects are higher.

It’s important to be treated for thyroid issues. If you think your thyroid may be the reason you’re having trouble conceiving, ask your doctor for a full thyroid panel test. Make sure you find out what your TSH (thyroid stimulating hormone) level is. The normal range, according to most doctors, is 0.5 to 5.5, but some endocrinologists believe that women with levels higher than 2.0 may have trouble getting pregnant, or may be at higher risk of miscarriages. You may want to find an endocrinologist to treat you if you’re worried that your thyroid level is affecting your pregnancy and your regular doctor is not taking the issue as seriously as you’d like.


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