What causes anovulation?

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What causes anovulation?

In general, the cause of anovulation is an imbalance of one or more certain hormones, especially the hormones involved in ovulation, which include:

  • Gonadotropin-releasing hormone (GnRH).
  • Follicle-stimulating hormone (FSH).
  • Luteinizing hormone (LH).

However, even hormones that aren’t directly involved in ovulation, such as testosterone and prolactin, can impact the hormones that are needed for ovulation. The following hormone imbalances and conditions can cause anovulation:

High levels of androgens (hyperandrogenism): Androgens are a group of hormones that help with growth and reproduction in both men and women. Typically, androgens are thought of as male-specific hormones, but the female body produces a small amount of androgen hormones, too. Androgens include testosterone, androsterone and androstenedione. Your gonads (ovaries or testicles) and your adrenal gland produce androgens. When a person with ovaries has a higher-than-normal level of androgen hormones in their blood, it’s called hyperandrogenism. The follicles in your ovaries contain eggs. A high level of androgens can cause these follicles to stay small instead of enlarging and maturing like they’re supposed to before ovulation. Conditions that can cause hyperandrogenism include:

  • Polycystic ovary syndrome (PCOS).
  • Obesity.
  • Adrenal gland issues.
  • Pituitary gland disorders, such as Cushing’s syndrome or acromegaly.
  • Certain medications, such as anabolic steroids.

Pituitary gland dysfunction (hypogonadotrophic hypogonadism): Your pituitary gland produces luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are needed for ovulation. If your pituitary gland isn’t releasing enough LH and FSH, it can cause anovulation. Conditions and situations that cause your pituitary gland to not release enough LH and FSH include:

  • Having a very low body weight, or body mass index (BMI).
  • Participating in long-term excessive or intense exercise.
  • Sheehan’s syndrome.
  • A pituitary gland tumor.
  • Damage to your pituitary gland.

High levels of prolactin (hyperprolactinemia): Prolactin is a hormone that’s released by your pituitary gland that’s mainly known for stimulating breast milk production (lactation). Prolactin also suppresses luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are needed for ovulation. Because of this, a high amount of prolactin in your blood can cause anovulation. Conditions and situations that can cause hyperprolactinemia include:

  • Breastfeeding.
  • A type of pituitary gland tumor called a prolactinoma.
  • Damage to your pituitary gland.
  • Damage to or illness of your kidneys, liver and/or thyroid.
  • Certain medications, such as psychotropic drugs, narcotics and drugs that treat ulcers or elevated levels of stomach acid.

Low levels of thyroid hormones (hypothyroidism, or underactive thyroid): Your thyroid — the butterfly-shaped gland in the front of your neck — produces two hormones that are needed for many important bodily functions: triiodothyronine (T3) and thyroxine (T4). Having a low level of thyroxine in your blood can increase the amount of prolactin your pituitary gland makes. Prolactin suppresses luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are needed for ovulation, so a low level of thyroxine can cause anovulation. Conditions and situations that can cause hypothyroidism include:

  • Hashimoto's thyroiditis, an autoimmune disease.
  • Thyroid surgery.
  • Radiation therapy.
  • Certain medications, such as lithium.

Low levels of gonadotropin-releasing hormone (GnRH): Your hypothalamus (a part of your brain) produces gonadotropin-releasing hormone (GnRH). GnRH triggers the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are needed for ovulation. Because of this, having low levels of GnRH in your blood can cause anovulation. Damage to your hypothalamus can cause low levels of GnRH.

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