How does thyroid dysfunction affect ovulation and overall fertility?

Does thyroid dysfunction prevent me from getting pregnant?

In general, thyroid hormones (known as T4 and T3) are essential for proper menstrual function, healthy ovulation, implantation of the fertilized egg, and placental function. Therefore, the thyroid gland must work properly for ovulation, conception, and maintaining pregnancy. Thyroid disorders — and consequently menstrual irregularities caused by thyroid issues — are quite common among women of reproductive age. For this reason, if several months pass without a pregnancy occurring, it is important to check for possible thyroid function disorders.

How does the thyroid affect fertility?

Sometimes — though not always — thyroid disease can affect your fertility. According to recent research, common problems caused by thyroid dysfunction include anovulation and menstrual irregularities. That’s why many women wonder, “I have Hashimoto’s — can I get pregnant?” The answer is yes, you absolutely can, but you may need some medical support.

Thyroid dysfunction can prevent ovulation by disrupting the balance of your body’s natural reproductive hormones. One way to determine if you are ovulating is by using our ovulation tests to see if your luteinizing hormone (LH) levels peak. LH is the hormone responsible for ovulation and stimulates the ovaries to release an egg. If there is too much or too little thyroid hormone, ovulation cannot occur.

Remember… even if your menstrual cycle is regular, you may still not be ovulating.

Additionally, some women experience a short luteal phase. The luteal phase is the time between ovulation and the start of menstruation. Normally, it lasts 13 to 15 days — long enough to “nurture” a fertilized egg. A short luteal phase may appear as infertility but is actually a failure to sustain a fertilized egg.

Scientists studying this topic in depth say that the exact mechanisms by which the thyroid affects fertility are not fully understood. However, thyroid problems definitely impact fertility. For example, hypothyroidism can increase prolactin — the hormone responsible for initiating and maintaining milk production after childbirth. Excess prolactin has a negative effect on fertility, sometimes preventing ovulation and sometimes causing irregular or absent menstruation. Elevated prolactin levels can result from an increase in a hypothalamic hormone called TRH (thyrotropin-releasing hormone), which stimulates the pituitary gland to release prolactin and TSH.

Some women with hypothyroidism also have polycystic ovaries or ovarian cysts, both of which can interfere with ovulation or cause fertility issues.

How can I get pregnant if I have thyroid issues?

All the above may sound discouraging, and a woman might wonder whether it’s worth trying — and how she can increase her chances of getting pregnant.

Yes, it’s absolutely worth trying, as there are many stories with happy endings! Don’t think of it as a long and painful process — simply as one that requires a bit of preparation before starting your conception journey.

First of all, talk to your doctor about when you should start trying to conceive. Here, pregnancy and preconception TSH levels play an important role. Many doctors believe that TSH levels of 3 mIU/L, 4 mIU/L, or even 5 mIU/L are acceptable in a woman trying to get pregnant. Generally, the normal thyroid range for a non-pregnant woman is 0.4–5.0 mU/L. Beyond that, the normal TSH levels during pregnancy are: 0.1–2.5 mIU/L in the first trimester, 0.2–3.0 mIU/L in the second trimester, and 0.3–3.0 mIU/L in the third trimester. In general, keeping TSH between 1 mIU/L and 2 mIU/L is considered ideal to help with both conception and maintaining a healthy pregnancy. High TSH levels — both before and during pregnancy — are not helpful.

Good luck!

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